All of NABF3
Other features of a DVD?
- Latent or manifest - Occurs when tired, daydreaming, or dissociated - Asymmetry is common - Challenging to neutralize - Pathophysio - unknown - Usually before age 3
Stereopsis testing?
- Lateral disparity tests - Random dot stereogram
How does intracolumnar feedforward and feedback work?
- Layers II and III project to V which signals back to the superior colliculus - Layers II, III, and V project to VI which signals back to the LGN
What is the Innate theory?
- Least accepted - AC is the cause of the strabismus, not the result of strabismus - AC is present at birth - Sensory anomaly that is present at birth
Primary vertical deviation management?
- Lens correction - Corrective or relieving vertical prism - Occlusion therapy if needed - VT (very difficult) - Establish BV in open visual space
Partial occlusion lenses?
- Lens-induced optical blur - Over-plus non-amblyopic eye - Fog enough to switch fixation to the amblyopic eye (glasses or CL)
Passive strabismus treatment?
- Lenses - Prism - Occlusion - Surgery - Botulinum toxin
Higher powered lenses and ACT?
- Lenses over 5.00 D - Plus lenses decrease measured angle of deviation - Minus lenses increase measured angle of deviation
CN VI paresis?
- Limited in abduction - More eso in affected DAF - May have ET in primary gaze - Face turn toward affected muscle
Atropine penalization for partial occlusion?
- Long-lasting cycloplegic instilled into non-amblyopic eye - Blurs the fixating eye - use amblyopic eye - Blur at distance and/or near
What is cross fixation?
- Looks like an abduction deficit, but just too lazy to bring eye out - Can tell diff with ductions because it shouldn't happen monocularly
Clinical characteristics of CI XT?
- Low AC/A - Pt may be strab at near and not distance - Decreased NPC and PFV ranges - NC and no amblyopia
Results: ATS 17 Levodopa
* Not a significant improvement
Ten years later: Atropine vs patching for moderate amblyopia?
* Residual amblyopia is common - Mean amblyopic eye acuity is 20/32 - Age <5 at entry associated with better VA - At 10, improvement in VA is maintained
Mohindra Ret problem: - You are scoping the vertical meridian (beam horizontal) and neutralize the reflex with a +3.00 lens - You are scoping the horizontal meridian (beam vertical) and neutralize the reflex with a +1.00 lens What is the net retinoscopy findings?
+1.75 - 2.00 x 090
What is the Brock-Givner Afterimage Transfer Test?
- AI vertical flash - fovea non amblyopic eye, cortically transfers to the fovea of the amblyopic eye - Patient must have normal correspondence - Fovea is tagged with AI - Compare fixation point to AI to evaluate
Contact lenses for total occlusion?
- AVT occluder - Nissel Naturals - Alden HP49 or Classic 38 - Orion Prosthetic lenses
Mechanical restriction noncomitant deviation?
- Abnormal muscle - Structural restriction
What if patient reports suppression in-instrument?
- Analyze frequency, laterality, size, and intensity of suppression - May have fusion on peripheral targets and central/foveal suppression
Etiologies of strabismus?
- Anatomical - Optical - Ocular disease - Innervational
What is a comitant deviation?
- Angle D is the same in all positions of gaze and with either eye fixating - Within 5 pd
What is the objective angle of deviation?
- Angle by which the visual axis of the deviating eye fails to intersect the target (zero point and fovea) - Manifest in strabismus and latent heterophoria * Cover test findings *
Features of harmonious anomalous correspondence?
- Angle of anomaly = objective angle - Point Z of the deviating eye has the same direction as the fovea of the fixating eye - Subjective angle is zero
Features of PAC Type I?
- Angle of anomaly is greater than objective angle - Often happens after surgery in patients that have previously had AC
What is the subjective angle of deviation?
- Angle of separation between the zero measure point (z) of the deviating eye and a point in that eye corresponding to the fovea of the other eye (point A) - Patient's perceived size of deviation
Features of sensory ET?
- Angle size is variable - May have amblyopia (relative amblyopia) - More common in younger patients (than sensory XT)
Variable features of Parks Monofixation syndrome?
- Anisometropia - H/o strab surgery - Amblyopia - EF - No strab on CT - ACT deviation > UCT deviation - AC
Optical etiology of strabismus?
- Anisometropia - High refractive error
What are cycloplegics?
- Anticholinergics - Block Ach - inhibit parasympathetic nerve impulses
What is fluoxetine?
- Antidepressant - Selective Serotonin Reuptake Inhibitor SSRI - Reduces intracortical inhibition - Increases BDNF
Pseudo ET features?
- Appearance of ET only - Facial appearance b/c of epicanthal folds and a wide, flat bridge of nose
What you ask the patient to do with Haidinger's Brushes?
- Ask the patient to monoclarly fixate a point on the MIT - Have the patient report where the brush is located (point to it) while fixating a central point
Prism based on Sheard's criteria?
- Associated measure - Amount in prism = 2/3 phoria - 1/3 compensating fusional vergence
Prism based on Percival's Criteria?
- Associated measure - Amount of prism = 1/3 greater lateral limit - 2/3 lesser lateral limit
Prism based on fusion?
- Associated measure - Amount of prism that gives a fusion response: on Worth 4 Dot or stereo testing
What is Point A?
- Associated point - Retinal point in the deviating eye, which when stimulated, gives rise to the same visual direction as the fovea in the fixating eye
Why is scoping on axis important?
- Astigmatism increases with increased eccentricity - Spherical component decreases with increased eccentricity
Treating constant XT?
- Attempt motor therapy at ortho position - If unsuccessful: * Suppression - stimulate at objective angle * AC - in-instrument motor stimulation
Results - binocular VA at 1 year?
- Avg 3.9 line improvement - Baseline 20/40 - 20/80 got 3.4 line improvement - Baseline 20/100 - 20/400 got 6.3 line improvement - 74% probability of 20/25 or better VA at 1 year
Suppression breakers?
- Awareness of correct response - Fast flashing - Blinking - Movement of suppressed target - Prism addition and removal - Pointing, single, and double - Changes in target parameters
What is the Hebbian model?
- Axon of Cell A is near enough to excite Cell B and repeatedly takes part in firing it, some growth processes or metabolic change takes place in one or both cells - Cells that fire together, wire together
Dark reared mice show decreased _______ in the visual cortex and the sensitive period is delayed = residual plasticity ______________
- BDNF - Persists longer than expected
Tests that indirectly determine the angle of anomaly?
- Bagolini Striated Lens Test - Worth 4 Dot - Major Amblyoscope - Red lens or maddox rod * Subject + objective = use equation *
Tests for AC?
- Bagolini Striated Lens Test - Worth 4 dot test - Major Amblyoscope - Red lens and maddox rod - Hering Bielschowsky After Image Test (HBAIT) - Haidinger's Brushes and Brock-Givner AIT - Cuppers Bifoveal test
Activities at ortho position?
- Bar reader - Bernell-o-scope - Colored filter activities - Pola-mirror - TV trainer - Vectograms/tranaglyphs - Dark room/penlight/R/G glasses
Corrective lenses for amblyope are based on?
- Based off a cycloplegic retinoscopy/refraction - Fully correct the ametropia
Spectacle prescription in the treatment of anisometropic amblyopia in children with refractive correction study?
- Based on cycloplegic refraction - Anisometropia, astigmatism, and myopia fully corrected - Hyperopia over 3D fully corrected or undercorrected by no more than 1.50D - Hyperopia under 3D, up to the investigator's discretion
Treatment strategy?
- Begin early in treatment sequence - Peripheral suppression eliminated first - Central/foveal suppression eliminated
How do we do diplopia awareness?
- Begin in a dark room, R/G glasses, pen light - Increase illumination - Remove R/G glasses
How do we develop normal peripheral fusion?
- Begin training with large targets at the objective angle of deviation - Eliminate peripheral suppression - Once you have achieved peripheral sensory fusion, work on peripheral motor fusion - Improve stereo - Diplopia awareness
Set up for ACT?
- Best corrected VA - Accommodative target - Select initial prism based on estimate from UCT - Fixate with normally fixating eye, then prism over deviating eye - Observe movement behind prism - Allow time to re-fixate
Who do we Rx prism for?
- Best for pts with normal sensory fusion - Rx prism because there is inadequate motor fusion
Presurgical treatment for patients with good binocular potential?
- Best optical correction - Amblyopia and EF eliminated - Normal sensory fusion established - Motor fusion ranges established maximally
Determining correspondence with a major amblyoscope?
- Best optical correction - First degree slides Step 1: Determine objective angle (can do a cover test in the machine) Step 2: Determine subjective angle Step 3: Douse test - Make sure the look at the center of the targets
Surgeries for ET?
- Bilateral MR recession - MR Recession/LR resection - Amount (and number of muscles) necessary depends on the angle of deviation - Early better, but you have to balance with anesthesia side effects (usually after 6 months, before 2 yr)
Watching movies to treat amblyopia study: Mezad-Koursh
- BinoVision or Sham - 60 minutes 6 days/week for 12 weeks - 88% compliance - Over 2 lines of acuity improvement
ATS 20 Binocular Dig Rush study?
- Binocular Dig Rush Game Treatment for amblyopia - Compare the efficacy of 1 hour/day of binocular gameplay 5 days per work plus spectacle correction VS spectacle correction only for the treatment of amblyopia in children 4 - under 13 years of age
Birch study on binocular treatment for amblyopia?
- Binocular treatment use dichoptic iPad games - Improvement in VA in patients that played game; no improvement in those with sham treatment
Clinical implications: Atropine vs patching for moderate amblyopia?
- Both patching and atropine are effective treatments for moderate amblyopia in patients 3 to under 7 years of age - VA improves sooner with patching - no significant difference at 6 months - Atropine - no significant side effects, easier administration, and lower cost - Clinically, we can use either patching OR atropine as initial treatment for amblyopia
Botox as an alternative to surgery?
- Botulinum toxin weakens the muscle - Binds presynaptically to prevent the release of ACh: Neuromuscular block
Neutralizing with ACT?
- Bracket, increase prism until you see first reversal - Record high neutral reading - Repeat with strabismic eye fixating (could not be actually - If pt has paretic deviation, it will change with strabismic eye fixating
What is fast flashing?
- Breakup of latency period needed for suppression - Flash target from suppressed eye to fixating eye and alternate
Two types of studies to determine the critical period?
- Brief deprivational studies - Reverse suturing studies
How much prism for IXT?
- Caloroso's residual vergence demand criteria - Leave around 10-15 prism demand - Trial frame
In-instrument sensorimotor fusion testing features?
- Can compensate for angle - zero motor demand - Reveals potential level of sensory fusion - Results may be very different than the out-of-instrument results
Determining the subjective angle with a major amblyoscope?
- Can pt see both targets? Alter illumination if no - Ask pt if targets are superimposed (at objective angle) - If not, have pt move targets until they are superimposed
What about Aniseikonia and Knapp's law?
- Can reduce aniseikonia by using CLs - Consider contact lenses and aniseikonia with our amblyopic patients
Diagnostic testing for non-accommodative ET?
- Careful versions/ductions - Comitancy testing - VA + refraction: amblyopia? Improve with plus? - Dilation important: sensory ET/XT presenting sign for retinoblastoma
What do you need to be careful with pseudo ET?
- Carefully determine RE: watch out for significant hyperopia - Careful monitoring and F/U 10-19% later diagnosed with ET
Sensory XT features?
- Causes by severe loss of vision in one eye (anisometropia, cataract, mac lesion, and retinoblastoma etc) - Large angle, constant, unilateral XT - More common in pts over 6 months with acquired vision loss - Up to age 5 = equal incidence of sensory ET and XT - Older patients more likely XT
Types of microtropia based on monofixation pattern?
- Central fixation - EF that is less than the objective angle - EF that is equal to the objective angle
Pratt-Johnson suppression size?
- Challenged classical theory of suppression - Binocular "field of vision" - Suppression zone for strabs without fusion covers the entire retina of the deviating eye (both nasal and temporal) except for a monocular temporal crescent
Diagnosis of accommodative ET?
- Characteristic onset - Response to lenses - Comitant deviation - Follow-up is important (stereoacuity)
Parks and monofixation syndrome?
- Characteristics commonly found in small angle ET - Especially as a post-op outcome of surgery for infantile ET
Neurologica/systemic disease with congenital vs acquired deviations?
- Congenital: Rare - Acquired: Frequent
Diplopia with congenital vs acquired deviations?
- Congenital: none unless decompensated - Acquired: Greater in one field of gaze
Abnormal head posture with congenital vs acquired?
- Congenital: present, patient unaware - Acquired: usually none, may have to so they can eliminate diplopia
Cover test with IXT?
- Consider doing CT at 20 ft or greater distance - Carefully repeat UCT giving time to refixate - Allow time to refixate on ACT
Features of infantile XT?
- Constant - Large angle at D and N (over 30) - Onset 2-4 months of age - Associated DVD in nearly 1/2 of patients - Large prevalence of underlying systemic or neurological disease
Constant infantile XT??
- Constant XT in a full-term infant is rare - R/o craniofacial or neurological defect
What are consecutive XT?
- Constant XT preceded by ET - Post-surgery - After correction with glasses
AC and the stability of strabismus?
- Constant angle - Stable angle - Comitant angle More stable = more likely = brain has one spot to adapt to
What is deprivation amblyopia?
- Constant physical obstruction along the line of sight - Prevents a focused image from forming on the retina - Most potential to cause severe vision los
When do we consider surgery based on frequency?
- Constant strabs of significant size almost always need surgery - Intermittent strabs depend on the amount of time patient is strabismic
The _______________ effect of dopamine on the _____________ of the horizontal cells, increasing their _____________ sensitvity
- Constrictive - Receptive field size - Spatial frequency
Function characteristics in Amblyopia are a difference in?
- Contrast sensitivity function - Vernier hyperacuity - Grating acuity - Crowding effect - Binocular summation and stereopsis
Sources of error in retinoscopy?
- Control accommodation - Make sure you are scoping ON AXIS
When do we use added plus lenses in the treatment of strabismus?
- Convergence excess (high AC/A): Esotropia - Equalize the angle at distance an d near: DE, accommodative ET's -Treat accommodative problems - Interim until pt can accept full plus Rx
Duane's ET classifications?
- Convergence excess ET - Basic ET - Divergence insufficiency ET
Duane's classifications of XT?
- Convergence insufficiency XT - Basic XT - Divergence excess XT
Overview of amblyopia treatment?
- Correct Refractive Error - Penalization Therapy - Vision Therapy - Treatment of Strabismus
What do we do for isoametropic amblyopes?
- Correct Rx - Follow every 6 weeks - VT if accommodative/eye movement problems
Treatment for strabismic amblyopia?
- Correct Rx - follow every 6 wks until resolved or no improvement - Add occlusion for 6 weeks until resolve or no improvement - If needed, increase tx or add - Taper treatment - Treat strab
Hubel and Wiesel conclusions?
- Correlated behavioral observations to physiologic and anatomical changes in the CNS - Demonstrated that visual deprivation occurs in the primary visual cortex
Presurgical considerations for patients with poor binocular potential?
- Cosmesis - Best optical correction - Improve amblyopia - If the patient has AC, how strong is the Anomalous motor fusion response?
When to Rx prism if they have AC?
- Cosmetic prism - Overcorrecting prism - want NC Does not happen commonly
Clinical Features of Parks Monofixation syndrome?
- Cosmetically straight eyes (under 10 pd) - Central suppression (no bifixation) - Peripheral fusion - No RDS stereo
What do you evaluate with sensorimotor fusion after the correspondence status is established?
- Current sensorimotor fusion - Potential for sensory fusion
What if my ET cannot accept full plus at distance?
- Cyclo therapy - Add at near - Gradually increase Rx: CL or glasses
DDx of OAIO?
- DVD - Secondary OA of IO due to paretic SO: *Paretic in primary gaze *Head tilt *(+) 3-step test
Infantile ET variable characteristics?
- DVD 50-90% - OAIO 78% - Low RE - Amblyopia - Cross fixation - Manifest nystagmus - Latent nystagmus - Anomalous correspondence (not common)
What are partial occlusion filters?
- Decrease both the light and form perception - Bangerter filters
Accommodation and amblyopia?
- Decreased amplitude of accommodation - Poor accommodative facility - Poor accuracy of accommodation
Contrast sensitivity and amblyopia?
- Decreased contrast sensitivity in patients with amblyopia - Decrease in intermediate and high spatial frequencies
What is relieving prism?
- Decreases vergence demand to help stabilize normal fusion
Things that can cause form degradation amblyopia?
- Dense central cataracts - Visually significant ptosis - Hyphema that blocks visual axis - Dense central corneal opacities - Dense vitreous opacities
Where do we start in the treatment sequence?
- Depends on the results of your strabismus evaluation - May have peripheral fusion, need to establish central fusion - May need to treat amblyopia and EF before moving on to binocular treatment
Adult dark-reared rats had what monocular deprivation responses like juvenile rats?
- Depressed VEP responses to stimulation of the MD eye - Potentiation of VEP response to stimulation of the good eye
What to do for dissociated vertical deviations?
- Determine if primary vertical also exists, associated conditions, Rx prism for primary vertical only - VT to establish/improve binocular vision: associated conditions - Surgical therapy
How do we test for AC?
- Determine the objective angle and subjective angle - indirectly determine the angle of anomaly - Directly determine the angle of anomaly
What was the goal of ATS 13?
- Determine visual acuity improvement in children with strabismic and combined strabismic anisometropic amblyopia treated with optic correction alone - Course of improvement - Factors associated with visual acuity improvement ( ocular alignment?)
AC evaluation?
- Determine which type is present using different testing methods - Determine if NC is present under ANY conditions - Re-evaluate correspondence status throughout therapy
Worth 4 dot and correspondence?
- Determines subjective angle
Binocular competition?
- Development of the synaptic connections between the neurons and the retention of these connections - Inputs from both eyes will compete for synapses onto the cortical binocular cell
Age of onset for AC?
- Develops only in strabismus that occurs early in childhood - Earlier the age of onset, the greater chance for AC
Surgery for primary vertical deviations?
- Deviations over 10-12 pd - If recent onset, monitor 6-8 months before referring for surgery
Why does it matter to define the type of amblyopia?
- Diff etiologies of amblyopia have different functional characteristics - Affects their prognosis - Monocular and binocular sensory deficits
What is wrong with the Snellen Chart?
- Different numbers of letters per line of VA depending on the acuity level - Letters have different degrees of difficulty - Differing influences of visual resolution - different surrounding contours on different lines - Assignment of acuity based on arbitrary # of letters missed
Free space activities and treating IXT?
- Diplopia awareness is important - 3rd degree to 2nd degree to 1st degree targets - Very important to train divergence too - Near to intermediate to distance
Unilateral cover test instructions for patient?
- Direct fixation to specific details on the target - Instruct patient to describe the target and keep it clear - May help to instruct the patient to look each time you cover: make sure attentive
Types of occlusion?
- Direct occlusion - Inverse occlusion - Alternating occlusion
Factors that affect AC treatment prognosis?
- Direction of deviation - Frequency of deviation - Magnitude of deviation - Type of AC - Stereopsis
When prescribing reliving prism, how much do we Rx?
- Dissociated prism criteria: ACT - Associated prism criteria: bothe eyes open
Problems with sensory theory?
- Does not account for UHAC - Can be errors in testing
Unstable fusion on worth 4 dot tells us?
- Double fusion - Limited sensory fusion ability - Fusional vergence is insufficient - Add prism or test at the objective angle in an instrument to evaluate sensory fusion
What does a paretic LSO look like on red lens test if it is placed over OS?
- Down and to the right largest separation - Red dot further away
Why would atropine be a better choice than patching?
- Duration of action - Good cycloplegic - blur the non-amblyopic eye - May improve compliance
Anatomical etiology of strabismus?
- EOM abnormalities - Abnormal content of orbit - Abnormal ligaments, tendons
Divergence insufficiency ET?
- ET at distance is > ET at near - Low AC/A
Basic ET?
- ET at near = ET at distance - Normal AC/A
Convergence excess ET?
- ET at near > ET at distance - High AC/A
What chart should we use to evaluate visual acuity in amblyopic patients?
- ETDRS chart - HOTV for younger patients
Features of a DVD on cover?
- Each eye turns up under the cover paddle - Spontaneous turning of one or both eyes upward when fatigued or inattentive - Eye moves down as it is uncovered - Appears to be a bilateral hyper deviation: Ddx hyper deviation - other eye is hypo
Surgical correction and infantile ET?
- Earlier is better: generally under 2 years but not under 6 months - Even with early surgery, many patients do not have normal sensory fusion
What are the benefits of the ETDRS chart?
- Early treatment of diabetic retinopathy study chart - Standardized crowding - Equal number of letters per line - More intervals of acuity
What do we treat in VT?
- Eccentric fixation - Accommodation - Eye movement - Eye hand coordination - Binocular vision: anisometropic amblyopia or strabismic amblyopia
What may impact the measured magnitude of ACT?
- Eccentric fixation - Both horizontal and vertical components to the strab - Far fixation distance - High power and anisometropic lenses - Near fixation distance prism measurements - Examiner accuracy
Atropine clinical pearls?
- Educate parents on potential side effects: facial flushing, tinted lenses in the sun - Check VA at near - may need to Rx bifocal for patient to read age-appropriate material
What do you see with an OAIOs?
- Elevation in adduction: over elevation - Horizontal version testing: R Hyper on L gaze and/or L Hyper on R gaze - Unilateral or bilateral: bilateral more common - Can be asymmetric
VT we want to do with a constant ET?
- Eliminate AC - Eliminate peripheral suppression - Improve peripheral sensory fusion and improve motor fusion around the angle of deviation
How do we develop normal central/foveal fusion?
- Eliminate central suppression with small targets - Increase vergence ranges
Establishing normal central fusion?
- Eliminate central/foveal suppression - Improve central/foveal sensorimotor fusion
Establishing normal peripheral fusion?
- Eliminate peripheral suppression - Eliminate AC - Improve peripheral sensorimotor fusion
Active therapy?
- Eliminate peripheral suppression: improve peripheral sensorimotor fusion - Eliminate central/foveal suppression: improve central/foveal sensorimotor fusion
What is psychogenic vision loss?
- Emotional or psychological origin rather than physical origin - Not produced consciously or intentionally - Truly experiencing symptoms - Substitution of physical signs - Sx for anxiety or emotional repression
Study design of ATS-7?
- Enrollment with spectacle treatment - 5 week f/u - 13 week f/u - 26 week f/u - 52 week f/u
Study design for ATS 13?
- Enrollment with spectacle treatment - 9 week follow-up - 18 week outcome exam - Post outcome follow-up every 9 weeks if VA still improving
Study design?
- Enrollment with spectacle treatment - Follow-up at 5 weeks - Continue to follow every 5 weeks until no improvement
When do we consider surgery?
- Esotropia over 20 pd - Exotropia over 25 pd - Vertical over 10 pd
Why treat AC?
- Establish normal binocular vision - May improve the stability of the angle after surgery
Amblyoscope for evaluating sensorimotor fusion?
- Evaluate at objective angle - Variety of second and third degree targets - Can accommodate large deviations - Can observe patient's eyes
What do you do if you find stable sensory fusion and no suppression in the in-instrument evaluation?
- Evaluate motor fusion ranges with second degree targets - Evaluate stereo by placing third degree targets at the objective angle
How do we describe EF?
- Eye - Direction - portion of the retina being used to fixate - Magnitude - how far from the fovea it is - Stability - steady vs unsteady
Botox procedure?
- Eye anesthetized - EMG inserted into the muscle - Move eye until muscle contracts - Small dose, 0.1 ml injected into muscle - In children, use anesthesia
How do you do forced duction testing?
- Eye grasped and moved in direction opposite to that which mechanical restriction is suspected - (+) forced duction = mechanical restriction
Adult dark-reared rats had decreased levels of _____________ and a return to the juvenile ___________
- GABA receptors - Juvenile NMDA receptors
Surgery for IXT?
- Generally for larger angles over 25-30 pd - Lateral rectus recession - Medial rectus resection - Recess-Resect
Why do we Rx lenses for strabismus?
- Give clearest image to each eye - Correct amblyopia - Reduce the size of the strabismic angle: make lens modifications - Improve sensory fusion: Need a clear image to each eye - Improved motor fusion skills
Why do we Rx lenses for amblyopic patients?
- Give the clearest image to each eye - Reduce the size of the strabismic angle - Improve sensory fusion - Improved motor fusion skills
Other features of Duane's Retraction syndrome?
- Globe retraction and narrowing of palpebral fissure on adduction - May have up/downshoot
Prognosis of treating acute onset comitant ET?
- Good if no pathology - Rx full Plus: Prism, VT, and Sx options too
Prognosis of accommodative ET?
- Good if short duration and intermittent at presentation - Good potential for normal binocular vision - If not corrected immediately, non-accommodative portion may develop. More likely to develop sensory anomalies
Overview of IXT treatment?
- Good sensory fusion - Most therapy can be done in free space - Diplopia awareness is important - Often have good peripheral fusion
Characteristics of intermittent exotropia?
- Good sensory fusion, good stereo - Amblyopia rare - When strabismic: diplopia, suppression (most common), and AC (may co-vary)
Features of accommodative ET?
- Gradually increase in frequency and duration - Moderate in size - Generally no AC: really variable angle
What is nutritional vision loss?
- Gradually progressive and painless loss of vision - Dietary insufficiencies: Vitamin B 1, 2, 6, 12 Excessive alcohol/tobacco consumption Central/cecocentral scotoma Temporal ONH pallor
How do we establish sensorimotor fusion at orthoposition with VT?
- Gross convergence: Brock String, 3 Dot Card - Fusional convergence: Smooth, step, jump **Diplopia awareness training is important** - IF AC, monitor with AI
Treatment arms of the levodopa/carbidopa study?
- Group A received 0.50 mg + 1.25 mg of levodopa/carbidopa per kg of body weight three times a day after meals with a protein rich drink - Group B received a placebo
Types of AC and ease of treatment?
- HAC and UAC are easier to treat - PAC is more difficult - PAC II is the most difficult
Subjective evaluation of EF?
- Haidinger's Brushes - Brock Givner Afterimage Test
What do we use for treatment of eccentric fixation?
- Haidinger's brushes - Afterimage transfer (normal correspondence) - Fast pointing
Types of anomalous correspondence?
- Harmonious anomalous correspondence (HAC) - Unharmonious anomalous correspondence (UAC) - Type I and Type II Paradoxical Anomalous Correspondence (PAC)
Performing UCT?
- Have patient fixation binocularly on a target - Cover one eye - Observe what the uncovered eye is doing - Chase the deviated eye - Allow pt time to refixate - Repeat 5-10x to determine frequency - Estimate magnitude
Blinking and suppression breaking?
- Have pt blink rapidly - May help eliminate suppression during therapy techniques
Neurological signs/symptoms warranting referral with an acute onset comitant ET?
- Headaches - ONH edema - Clumsiness, ataxia, and gait imbalance - Nystagmus - Nausea/vomiting - Enlarged head size Most have neurological signs and symptoms, but rarely can have no other signs or symptoms
Set up for Maddox Rod/Red lens testing?
- Help confirm underacting muscle observed on version testing - Maddox rod or red lens placed in front of 1 eye - Pt fixates on penlight at 40 cm - Use pathological diplopia
Why do we want to establish diplopia when the eye deviates?
- Helps patient regain control of the deviation
How do we diagnose co-variation in our IXT pts?
- Hering-Bielschowsky AI test - Determine correspondance with eyes aligned and again when eye turned
Subjective testing to evaluate comitancy?
- Hess Lancaster Test - Maddox Rod Test - Red Lens Test - Double Maddox Rod Test
What was the binocular therapy like for ATS 18?
- Hess falling Block game played on an iPad - Contrast reduced in the sound eye
In-phoropter motor fusion testing?
- Heterophores and some intermittent strabismic patients - High-frequency intermittent strabs (small apertures reduced peripheral fusion)
Out-of Instrument method uses?
- Heterophoria patients - Intermittent strabismic patients with sufficient motor fusion ability to maintain alignment
Frequency?
- Heterophoric - Intermittent strabismic - Constant strabismic
How does interferometry work?
- High contrast interference fringes projected on the retina - Ask patient to identify the orientation of the fringes - Bypasses sensory and motor deficits that decrease acuity
In-instrument method uses?
- High frequency intermittent strabismic patients without sufficient motor fusion ability to maintain alignment - Constant strabismic patients
AC treatment and frequency of strabismus?
- Intermittent strabs often have co-variation = improved prognosis - Constant strabs more often have AC under ALL viewing conditions
What can you do to make sure you scope on axis in strabismic patients?
- Introduce prism over the fixating eye - Perform out of the phoropter - Align yourself with the eye
Comitancy testing*questions?
- Is deviation comitant or not? - IF deviation is noncomitant: *Identify the underacting muscle *Determine if it is paretic - Paretic deviation: is it recent onset?
Concerns with atropine instead of patching?
- Is it as good as patching? - Are side effects an issue
Unilateral cover test tells us?
- Is strab present or not? - Direction, Laterality, and Frequency
Final thoughts on lens correction?
- Kids adapt much more easily than adults - Always take the binocular status into account - Don't be afraid to Rx a bifocal
Single and double pointing for breaking suppression?
- Kinesthetic feedback breaks suppression - Double pointing method breaks foveal suppression in the stereoscope
Why add Carbidopa to Levodopa?
- L-dopa is converted to dopamine in PNS but has many toxicities - Carbidopa added lets it cross the blood brain barrier and convert to dopamine in the CNS - Dopamine is stored in the vesicles and released through synapses
Function of the LGN?
- LGN receives retinal signals and transmits them to the cortex without much processing - Signals for left and right eyes remain segregated into different layers
Subject requirements for ATS 13?
- Strabismic or combined mechanism amblyopia - RE one of the following: ≥ 1.00D SE aniso, ≥ 1.00D astigmatism, ≥ +2.00D SE hyperopia in either eye - VA measured at baseline and every 9 weeks - Ocular alignment - simultaneous prism cover test and stereoacuity
PAC II features?
- Subjective angle is greater than objective angle - Often after surgery in patients that previously had AC
Features of unharmonious anomalous correspondence?
- Subjective angle is less than the objective angle, but greater than zero - Angle D > Angle S > 0 - Anomalous angle does not equal objective angle
What is toxic vision loss?
- Sudden, bilateral vision loss, central scotoma - Exposure to: Methanol Quinine Mercury Lead Cocaine
CN III paresis if partial?
- Superior division = SR and levator - Inferior division = MR, Sphincter, and CB
Sensory elements that can influence prognosis?
- Suppression - Stereopsis - Amblyopia - Sensory fusion? - Motor fusion?
Alternating suppression?
- Suppression is in the deviated eye, suppression alternates as the eye does - Changes in fixation rapidly - response on tests simulates a sensory fusion response
Intensity with worth 4 dot responses?
- Suppression with lights on only = shallow - Suppression in the dark = deep
Primary vertical deviations and sensory processing?
- Suppression/suspension - May have amblyopia if constant strab - May have AC with horizontal and/or vertical component: primary comitant small-angle strabismus
Haidinger's Brush + After image transfer measures what?
- TOTAL angle of anomaly directly (no equations)
Why is anisohyperopia more common?
- Takes less refractive error to get there - Hyperopia is much more common in young children
Motor fusion and target position?
- Target at strabismic angle - Target at different demands - Target at zero demand
What is the douse test in the major amblyoscope?
- Tells us if objective angle matches subjective angle - After superimposition is reported - Turn off fixating eye - UCT - No movement = NC - Movement = AC MOVEMENT SEEN ON DOUSE IS THE ANGLE OF ANOMALY (still have to calculate)
What is a tenotomy?
- Tendon completely transected - Weakens action - SO
How do you use Bagolini Striated lens test?
- Test conditions are similar to normal viewing conditions (least dissociating, most natural) - Pt fixates a light at 1 m - Pt reports what is seen (OD, OS, OU): drawing helps - Determines subjective angle
From Mitchell (1991)'s study on the long-term effectiveness of different regimens of occlusion in MD Kittens: The improvement in VA with the good eye patched full time?
- The improvement in the VA is not retained once the kitten was given binocular visual output - The VA in the good eye was reduced compared to its initial VA
What is direct occlusion?
- The most common form used in amblyopia - Occlusion of the non-amblyopic fellow eye
What happens if you visually deprive both eyes of the adult rat before the monocular deprivation?
- The visual deprivation reactivated the rapid ocular dominance plasticity - Monocular deprivation was effective and the adult rats behaved like juvenile rats - Effects lasted for several days
Cycloplegic refraction drop regimen? **
- Topical anesthetic (usually) - 2 gtts cyclopentolate (1% for children >= 1 year, 0.5% for children < 1 year) - Phenylephrine or tropicamide for mydriasis - Wait 30 minutes
Treatment for secondary vertical deviation?
- Train convergence, re-evaluate for primary vertical deviation - Treat horizontal deviation
Three most common causes of noncomitant deviations in adult patients?
- Trauma - Vascular problems - Neoplasm
Three causes of underacting muscles?
- Trauma itself is paretic - Mechanical - faulty insertions, tendon abnormalities - Innervational - impairment of cranial nerves
How do we improve monocular function?
- Treat amblyopia - Improve accommodation: monocular accommodative therapy - Ocular motility - Fixation, Pursuits, Saccades
How do we improve monocular visual function?
- Treat amblyopia - Normalize monocular skills: accommodative and ocular motility therapy ** Re-evaluate correspondence testing after amblyopia treatment
Active vision therapy for primary vertical deviation?
- Treat monocular skills first - Vertical vergence ranges - Vectograms - Eccentric circles - Stereoscope
What is Project LUMA?
- Treating amblyopia in the dark - Refractive amblyopes over 18 - Live in darkness for 5 and 10 days - VT 3 weeks before and 5 weeks after
Amblyopia treatment study 5 looked at?
- Treatment of anisometropic amblyopia in children with refractive correction - Evaluate the effectiveness of refractive treatment alone for the treatment of anisometropic amblyopia in children 3 to under 7 years old
Some techniques to find out if someone is malingering?
- Trial frame with +/- 0.12 lenses - Frames with plano lenses - Trial frame refraction using lenses that cancel each other - Different VA optotypes - Measure VA starting with 20/10
+3.00 lens test?
- True DE has a high AC/A ratio - Simulated DE is basic XT so normal AC/A - Do cover through +3.00: True DE = near angle equalize or exceed distance angle Simulate DE = no significant change in near angle
Stable fusion with no suppression on worth 4 dot tells us?
- True fusion or HAC to UCT to differentiate - Fusion response = normal second-degree fusion - Sufficient motor fusion to align eyes
Combination refractive/non-refractive accommodative ET?
- Type of accommodative and partial accommodative ET - Correction of distance Rx and bifocal - Distance to align and near to align (CE of some sort)
Non-refractive accommodative ET?
- Type of accommodative and partial accommodative ET - High AC/A - Patient needs bifocal - Refraction does not correct tropia - Could be a myope with super CE
Refractive ET?
- Type of accommodative and partial accommodative ET - Moderate/high hyperopia - Angle will straighten with refractive correction
Optical correction considerations for amblyopes?
- Type of refractive error - Magnitude of refractive error - Direction of deviation - Size of deviation - Will the optical correction impact sensory and motor fusion
What to consider for optical corrections?
- Type of refractive error - Magnitude of refractive error - Direction of deviation - Size of deviation - Will the optical correction impact sensory and motor fusion?
A-pattern features?
- UA of IO and secondary OA of SO - In down gaze, horizontal action of the SO is abduction
V-Pattern features?
- UA of SO, secondary OA of IO - In up gaze, horizontal action of IO is abduction
Treatment of ET with over 15 pd and under 15 pd angle of anomaly?
- UAC/PAC II - Combined sensorimotor stimulation
How can the sensory theory explain UHAC?
- UHAC is initially HAC - UHAC occurs following a change in objective angle - Point to a large area of correspondence in AC versus point to point correspondence in NC
Set up for version testing?
- Uncorrected - Move eyes binocularly into each diagnostic action field - Observe it the non-fixating eye lags (UA) or excessive movement (QA)
Differential diagnosis of vision loss?
- Uncorrected refractive error - Amblyopia - Organic vision loss - Psychogenic vision loss - Malingering
Lens modifications we can make to change the size of the angle of deviation?
- Under Corrective lenses - Over Corrective lenses - Added plus at near
Measuring angle kappa?
- Under monocular conditions - Generally symmetrical
CN VI causes in adults?
- Undetermined - Neoplasm - Trauma - Vascular
Accommodation and anisometropia?
- Unequal demand - Generally driven by the eye with the least ametropia
Different cover tests?
- Unilateral cover test (UCT) - Simultaneous prism cover test (SPCT) - Prism alternate cover test (PACT) / alternating cover test (ACT)
Patient presentation for microtropia with identity?
- Unilateral decrease in VA - No strabismus or hx of strabismus - No amblyogenic RE - No obvious organic cause
Ocular motility and amblyopia?
- Unsteady fixation - Increased tendency to drift during fixation - Saccades - under and overshoots - Pursuits - jerky, irregular movement
Subject requirements for the treatment of anisometropic amblyopia in children with refractive correction study?
- Untreated anisometropic amblyopia - Difference of 3 or more logMAR lines - Anisometropia of ≥ 0.50D of spherical equivalent and/or ≥ 1.50D astigmatism - No strabismus
What is a tubular visual field?
- Use a tangent screen - Examine at 50 cm then 150 cm - The visual field does not expand in size between the two like you would expect. Stays the same.
Clinical pearls for accommodative ET?
- Use an accommodative target during cover test - Make sure the patient is keeping the target clear - Have pt report what is on the target
Sensory stimulation in XT?
- Used if unable to stimulate a convergence response - Full time occlusion during therapy
What is over correcting prism?
- Used to treat ARC - Disrupts the ARC Pts who are unable to do active tx
Features of the Maculo-Macula test of Cupper (AKA Cupper's Bifoveal test)
- Useful for evaluating small angle of anomaly when EF is present - Patient fixates on an object with a normal eye (mirror used) - Examiner places visuoscope target centered on fovea of non fixating eye - Pt reports what is seen
Features of visuoscopy?
- Uses direct ophthalmoscope - Objective - Uses foveal light reflex - Monocular
What is Haidinger's Brushes?
- Uses the Macular Integrity Tester (MIT) - With the MIT, you can view the entopic phenomenon Haidinger's Brushes
Longstanding strab?
- Usually no diplopia - Comitancy may have spread - May have slight anomalous head posture - Old photos show anomalous head posture - May have amblyopia
Abnormal head position?
- Usually turn head toward the paretic muscle - Eliminates diplopia - Fixating eye in most comfortable position - Ocular torticollis
Which of the following tests are affected by EF? - VA - Worth 4 dot test - Cover test - Stereo acuity
- VA - Cover test
Results for PEDIG - ATS 2A?
- VA improved in both groups to a similar degree - After four months, both groups improved 2.4 lines in VA - VA was at least 20/32 and/or improved from baseline by 3 or more lines in 62% of the patients in both treatment groups
Clinical implications: Will increased patching improve acuity in residual amblyopia?
- VA improved with both 2 and 6 hours of patching - Acuity improved in patients with residual amblyopia who had previously patched for 2 hours more with 6 hours of daily patching - Residual amblyopia, increase patching time
Results at week 5?
- VA improvement with spectacles averaged about 1.8 lines - 59% of patients improved 2 or more lines - 11% no improvement - 7% met criteria for resolution
Results of the PEDIG ATS 2B?
- VA in the severe amblyopic eye improved a similar amount in both groups - Improvement from baseline to 4 months was 4.8 lines in the 6 hour group and 4.7 lines in the full time group
Resolution of amblyopia in the study?
- VA within 1 line VA - Related to better baseline VA - Inversely related to the magnitude of anisometropia - No relationship to age
What is a retinomotor value?
- Value each photoreceptor has - Proportional to the distance from the fovea - Guides amplitude of saccade needed to fixate object - Increases as we move toward the periphery
Uncorrected astigmatism and acuity?
- Variable effect on acuity - Decreased vision may decrease sensory fusion
Features of basic exotropia?
- Variable onset - Exo is approx equal at distance and near - Normal AC/A - Good stereo but may have poor 1 and 2ndary fusion (worth 4 dot problems) - Suppression and co-variation common (NC when aligned, HAC when strabismic)
Features of divergence excess exotropia?
- Variable onset - Exodeviation is larger at distance than at near - Large angle at distance, small angle at near - High AC/A
CI XT features?
- Variable onset - Symptoms of near asthenopia - Exo near > distance
Positive response on 4 BO test?
- Version + no vergence movement - Place prism over deviating eye and should see no movement of the fixating eye
Negative response on 4 BO test?
- Version + vergence movement
When might you see an A or V pattern?
- Versions - Detected usually on ACT though
What is a variable vertical deviation?
- Vertical deviation that fluctuates in its presence and size, the direction remains the same - Often seen with reduced sensory skills, may stabilize as sensory skills improve - Re-evaluate vertical deviation as sensory fusion improves - Consider diagnostic occlusion
Prism addition and removal for breaking suppression?
- Vertical prism - Move image in and out of the suppression zone (aware when it is out, then move it back in and make sure they are still aware)
Head or chin elevation/depression, suspicious of which muscles?
- Vertically acting muscles - Different in horizontal deviation - A or V pattern strabismus
NMDA receptor and plasticity?
- Visual deprivation reactivates ocular dominance plasticity in adult rats - Activation of the NMDA is required for activity - dependant synaptic plasticity
_____________ is required as a signal to start the critical period of development and it is associated with _________.
- Visual stimulation - The retina being exposed to light
What is a spread of comitancy?
- Weakness of paretic muscle - OA of direct antagonist - Contracture of direct antagonist - Deviation spreads into all DAFs - Becomes increasingly comitant
Good candidates for esotropia surgery?
- Wearing a maximum hyperopic correction - No amblyopia or minimal amblyopia - Normal sensory fusion - Good motor fusion around the angle of deviation
How do we increase treatment if initial treatment is atropine?
- Weekend atropine - Daily atropine - Add optical penalization (plano lens) - Add patching - Office based VT
Clinical implications: Is daily atropine necessary?
- Weekend atropine is as effective as daily atropine in children 3 - under 7 years old with moderate amblyopia - Improvement in VA is similar to that seen with patching - Weekend atropine can be used clinically to treat amblyopia
What is the crowding effect?
- Well known deficit in amblyopia - Contour interactions create an interference effect that can reduce acuity
In addition to cycloplegic Rx consider what?
- What prescription best aligns the eyes at distance and near? - What binocular prescription gives the best sensory fusion? - Anisometropia
How do you measure the direction of EF?
- Which portion of the retina is being used to fixate? - Relative to the fovea
PAC II eso vs exo?
- Will subjectively report a much larger angle than objectively measured - Will say they are more eso than you measure
What is the competition theory?
- With both eyes sutured, the cats did not go completely blind. Still some acuity - No shift in ocular dominance columns - Equally deprived
Can suppression and AC co-exist?
- YES - Suppression can make evaluating AC difficult - Eliminate suppression in a patient with poor prognosis for sensory fusion can cause intractable diplopia!!!
Subjective refraction in amblyopia/strabismus?
- Young children usually poor responders - Amblyopic patients have a larger just noticeable difference than the typical 0.25 used in subjective
Ocular disease etiology of strabismus?
- Younger children more likely to develop ET - Older children and adults more likely to develop XT
What does it mean to be a dark reared cat?
- Zero light exposure hits the retina for 4 months (different than lid suturing) - No visual experience - Then the car is monocularly deprived and reared normally
What is Point Z?
- Zero measure point - Retinal point in deviating eye which receives the image of the object fixated foveally by the nondeviating eye
What is an esotropia?
- Manifest deviation - Visual axes cross in front of the point of fixation - Inward or convergent misalignment of the eyes
What is exotropia?
- Manifest outward deviation of one eye from the position of bifixation
Issues with the 4 BO test?
- Many atypical responses found in both normal and abnormal patients - Patient reporting diplopia is not diagnostic of a (-) test - Not repeatable
Other methods for diagnosing EF?
- Maxwell's Spot - OCT imaging
Recent onset noncomitant deviation children symptoms?
- May have no complaints - Head turn, tip, or tilt may be noted
Constant ETs and extending normal SMF to free space?
- May have normal sensory fusion in-instrument - Extend fusion to all distances - IF you cannot not establish normal BV in free space: Rx prisms/added lenses or refer for surgery
Treatment of AC in exotropia?
- May overminus but leave residual angle: reduce size of angle, stimulate convergence = covariation - Occlusion - Motor stimulation - Sensory stimulation
Angle Kappa and strabismus?
- May simulate, conceal, or exaggerate strabismus
How much did vision improve overall?
- Mean of 2.9 +- 1.8 lines - 77% improved ≥ 2 lines of VA - 60% improved ≥ 3 lines of VA - 27% had resolution of amblyopia
Three causes of overacting muscles?
- Mechanical: muscle insertion/tendons - Idiopathic - Hering's law of equal innervations
Small angle esotropia types?
- Microtropia - Microtropia with identity - Monofixation syndrome
Small angle ETs?
- Microtropia - Monofixation syndrome
Management of IXT options?
- Monitor - Refractive correction - Overcorrection - Patching - Prism - Vision therapy - Surgery
Covariation and HBAIT?
- Monitor for eye position changes - Correspondence status will change for these patients when strabismic vs aligned - Intermittent tropes: never diplopic
How do you do near (Mohindra) retinoscopy?
- Monocular - Dark room - 50 cm - Pt fixate the light - 1.25 D is subtracted from sphere - Useful if unable to cyclo
How did Mitchell do part-time occlusion on kittens?
- Monocularly deprived until 6, 8, and 10 weeks of age - The non-deprived eye is occluded for part of each day - kitten allowed binocular visual exposure - Occlusion of 3.5 hours vs 5 hours per day
Treatment of AC and esotropia?
- More challenging than XT - Motor stimulation is limited by divergence ability - Size of the objective angle and anomaly angle determine which type of treatment
Magnitude of strabismus and AC?
- More common in small and intermediate angles of strabismus - Common in microstrabismus - Very uncommon in angles over 30-40pd
Etiologies of CN IV paresis?
- More commonly congenital: Family Album Testing - Can be trauma, undetermined, but rarely aneurysm or neoplasm
Decreased latency?
- More difficult to suppress - Blinking or flashing targets
Now that I've done cyclo ret, how do I Rx?
- More plus will be found than can be prescribed (normal ciliary muscle tonus will be relaxed, not just accommodation) - Subtract a minimum of 0.50 - 1.0 D from the wet retinoscopy findings - How much also depends on the type of refractive error and binocular status of the patient
Results of the levodopa/carbidopa study?
- More than 2 lines improvement in VA was greater in the levodopa than in the placebo group - Greater improvement in patients younger than 8 years old - No significant reversal of the improved VA at 6 month f/u
Frequency of exotropes?
- Most XTs are intermittent and convergence is a strong motor response (can be intermittent at one distance and constant at another - Some XTs are constant but its not as common - Rarely constant and unilateral
Motor stimulation?
- Most common - Co-variation occurs with vergence - Angle of anomaly decreases with increased fusional vergence (as pt approaches ortho) - When bifixating target at ortho position: NC present
CN IV paresis features?
- Most common cause of vertical deviation - Hyperdeviation of affected eye - Unable to depress eye when adducted - SOTO = Superior Oblique Tilt Opposite
Who does intermittent XT present in?
- Most common type - Usually presents early in childhood - Often seen in neonates, but any X over 6 months is abnormal
Summary of XT?
- Most often intermittent - Rarely constant and unilateral - Generally good sensory fusion - Evaluate correspondence - Evaluate 2nd and 3rd degree fusion - Evaluate control of deviation
Prescribing for esotropia + hyperopia?
- Most plus to correct ametropia at distance and near - Consider a bifocal to help accept full plus
Why is evaluating correspondence challenging?
- Most testing requires subjective responses - Test results are often variable - Test results are contaminated by EF
Out-of-instrument sensorimotor fusion testing features?
- Motor fusion is poor = may result in suppression/poor sensory fusion - May result in a lower level of sensory fusion than is actually present - Patient's habitual level of sensorimotor processing
Treatment of esotropia less than or equal to 15 pd and any angle of anomaly?
- Motor stimulation - Sensory stimulation
Comitancy and ACT?
- Move target into 9 DAF and neutralize - Test with one eye fixating, then the other - Sensitive to small differences
What is resection?
- Muscle is disinserted and a portion is excised and reattached to the original site of insertion - Strengthens muscle action
What is a recession?
- Muscle is disinserted and reattached to the globe at a position posterior to the original insertion - Weakings muscle action
Innervational etiology of strabismus?
- Muscle tonus or innervational changes: intoxication, meds, trauma, and disease - Innervational anomalies: congenital, high or low Ac/A
Prescribing corrective prism?
- Must have NC and normal peripheral sensory fusion - Rx corrective amount: titrate slowly and monitor angle of deviation and sensory fixation
How do we use afterimage transfer for eccentric fixation treatment?
- Must have normal correspondence!! - Cover good eye and move after image to certain targets like hart chart. When moved in the right spot = clearer
Features of strabismic amblyopia?
- Must occur before the age of 6 - Constant/Unilateral strabismus
With centration therapy, NC may occur where?
- NC may occur at a centration point - VT activities - Place object closer than centration point convergence: NC
Sensory fusion and naturalness?
- Natural targets are most difficult for constant strabismic patients - Patients with good sensory fusion have an easier time fusing natural targets - More natural targets retain AC/suppression
Testing suppression size with worth 4 dot?
- Near = peripheral: about 6 degrees at 40 cm - Distance = central: about 1 degree at 6 m
What can make you look less exophoric?
- Negative angle Kappa - Wide bridge of nose - Presence of epicanthus - Small pd - Wide face
What can make you look more esotropic?
- Negative angle Kappa - Wide bridge of nose - Presence of epicanthus - Small pd - Wide face
CN VI causes in children?
- Neoplasm - Trauma - Elevated ICP
What do we do if there are both horizontal and vertical components to the strabismus?
- Neutralize the larger component first - Stack prisms?
Clinical characteristics of DE XT?
- No amblyopia - Suppression and co-variation common - Panoramic vision - May have simulated DE
Results: ATS 20 older cohort 7-12 years of age
- No improvement in letter score after 8 weeks - 58% completed > 75% of prescribed treatment - iPad game was not found to be beneficial to either acuity or stereoacuity
Does blind spot syndrome exist?
- No known mechanism for continuous motor readjustment - Small size of ONH - Objective angle would be different at different fixation distances - Objective angle would be different in different fields of gaze
Helveston and von Noordern clinical picture of microtropia?
- No movement UCT - HAC - (+) 4 BO - Amblyopia - EF = objective = A - Peripheral fusion - Gross stereo - Second degree fusion
Divergence insufficiency features?
- Non-accommodative ET - Distance angle > Near angle - Mostly older pts: may be decompensated EP - Comitant - R/O any neurological cause: esp look for abduction deficit
Treatment goal of re-establishing NC?
- Normal sensorimotor fusion established in-instrument - Goal of normal sensorimotor fusion in free space: need to remediate strabismus
Features of psychogenic vision loss that is different than malingering?
- Not purposeful - Not produced consciously or intentionally - Truly experiencing symptoms - Tubular visual fields common
Target detail and sensory fusion?
- Number and position of contours - Patients with poor sensory fusion = suppression of detailed targets - Patients with good sensory fusion = suppression of detail free targets
Challenges with ACT?
- Nystagmus - Rebound saccade - Inappropriate target - Inappropriate Instruction - Poor fixation - Examiner sensitivity
What is the Hirschberg test?
- Objective evaluation of alignment - Use position of corneal reflexes relative to center of pupil - Good for young pts - minimal pt cooperation is necessary - Determine presence of strabismus, direction, laterality, and estimate frequency/magnitude
Determining refractive error in strabismic/amblyopic patients?
- Objective measurement is VERY important - Subjective may be unreliable
What is alternate cover testing measuring?
- Objective measurement of the angle of deviation - Magnitude without fusion
How do you do visuoscopy?
- Objectively evaluating which part of the retina the patient is using to fixate - Project a calibrated target on to the retina as the patient fixates at the center of the target - Observe the area of the retina that the patient is using to fixate
Objective testing to evaluate comitancy?
- Observation - Version testing - Duction/forced duction tection - Cover test in all diagnostic fields of gaze - Park's 3 step
Why treat suppression?
- Obstacle to testing correspondence and sensory status - Obstacle to creating normal sensorimotor fusion
What is Flom's Swing?
- Obtain anomalous sensory fusion at the subjective angle - Improve anomalous divergence - Obtain alignment with the eyes - Re-evaluate correspondence with eye straight
Tagging eyes with HBAIT?
- Occlude deviating eye, flash fixating eye with the horizontal flash - Occlude fixating eye, flash the deviating eye with the vertical flash - Uncover both eyes = ask if both AIs are seen at the same time: blink quickly to help see lights
Occlusion test?
- Occlude for 30-45 minutes - Near deviation increases = simulated DE - No change in near deviation = true DE
Causes of acute onset comitant ET?
- Occlusion - Physical or emotional shock or stress - IDiopathic - Neurological causes
IXT Treatment success?
- Occlusion 37% - Overminus 28% - Prism 28% - Surgery 46% - VT/Orthoptics 59%
How do we tell diff between true DE and simulated DE?
- Occlusion test - +3.00 lens test
Common signs and symptoms of IXT?
- Ocular discomfort - Blur D and N - Headaches - Diplopia - Monocular eye closure in bright sunlight - Cosmesis concerns - No symptoms with suppression or AC
How would ocular pathology present differently than amblyopia?
- Ocular disease or structural anomaly - Unilateral or bilateral - Sudden onset or progressive - May have: APD, color vision defect, visual field defect
How do we assess visual efficiency?
- Ocular motility - Accommodative function - Intermittent strabismus and heterophoria: monocular and binocular evaluation - Constant strabismus: monocular evaluation
What is organic vision loss?
- Ocular or neurological pathology or structural defect - Nutritional - Toxic
IXTs and frequency?
- Often exhibit a variable frequency over time - Different control at different times of the day or if daydreaming - May exhibit deviation more if patient is tired or sick
Comitancy of vertical deviations?
- Often non comitant Need to do comitancy testing + Park's 3 step
Who do we treat with VT?
- Older patients with amblyopia - Younger patients that plateau with patching - Patients with eccentric fixation
VA and anisometropia?
- One eye blurred at all times - May use one eye for distance and one for near - If large enough, one eye is never used
Non-registered movements and the motor theory?
- Only producing eye movement, do not change the egocentric direction - Neural impulses only communicate with EOMs Accommodative vergence
Features of infantile ET?
- Onset before 6 months of life - Non-accommodative - Large angle of 40 to 60 pd - Constant angle - Normal CNS
Infantile ET?
- Onset is under 6 months of age - Usually non-accommodative
Acquired XT?
- Onset over 6 months - Sensory XT - Mechanically restrictive or paretic XT - Primary XT: Constant or Intermittent
Infantile XT?
- Onset under 6 months - Mechanically restrictive or paretic XT
Maintaining BV efficiency?
- Optical correction - Home therapy - More frequent follow-up
General management strategy for treating strabismus?
- Optimal refractive prescription - Develop sensory and motor fusion - Establish binocular vision in free space - Maintain and monitor pts binocular status
Sequential management of ET?
- Optimum refractive prescription - Improve monocular visual function - Develop sensory and motor fusion - Establish binocular vision in free space - Maintain and monitor patient's binocular status
Movement of a suppressed target?
- Oscillate the suppressed target within the suppression zone - "Chasing" the target - Change the demand of the target
Yoked prism?
- Parallel base - Non-comitant deviation - Nystagmus - VF loss
Causes of noncomitant deviations?
- Paretic (neurogenic) - Mechanical restriction (myogenic)
Management of IXT with patching?
- Passive anti-suppression therapy - Decrease magnitude of deviation? - Change strabismus to phoria?
Over Correcting prism treatment for AC?
- Passive treatment - First evaluate anomalous motor fusion with the progressive prism adaptation test - Full time occlusion with 2 30 min sessions per day of prism wear (hand eye activities during sessions and frequently monitor correspondence)
Running version testing?
- Pat follows target into every DAF - Add hirschberg will increase sensitivity (move you and penlight) - Keep target stationary, move pts head
How do we taper patching 2 hours/day?
- Patch 1 hour/day x 6 weeks - Patch 1 hour every other day x 6 weeks - Stop - F/u after 6 weeks
How do we increase treatment if initial treatment is patching in moderate amblyopes?
- Patch 2 hours/day - Patch 6 hours/day - Full-time patching - Add daily atropine - Office based VT
How do we increase treatment if initial treatment is patching in severe amblyopes?
- Patch 6 hours/day - Full-time patching - Add daily atropine - Office based VT
Awareness of correct response?
- Patient is aware of what he/should be assessing if suppressing and if not suppressing - Patient will attempt to attend to suppressed target
Procedure for 4 BO test?
- Patient views a target and a 4 pd is placed over the fixating eye - Positive or negative response
Random dot stereogram?
- Patients must be bifoveal - High frequency intermittent strabismic patients will often have RDS stereo but not constant strabs
Sensory stimulation for treatment of esotropia less than or equal to 15 pd and any angle of anomaly?
- Patients that do not respond to motor stimulation - Foveal and small central targets - Peripheral targets: may have anomalous fusion
AC treatment and steroposis?
- Patients with AC may have lateral disparity (local stereo) - No RDS unless pt is bifoveal: patient must have NC under some condition
How long does botox last and when is the peak?
- Peaks 24-48 hours, maximum weakening at 2 weeks - Lasts approx 3-4 months - Longer lasting with repeated tx
According to the IOT, when does the critical period for binocularity in humans peak and diminish?
- Peaks at 1-2 years - Diminishes until age 7-8
How to describe intermittent strabismic?
- Percentage of time strabismic (POTS) - Percentage of time troped (POTT) Redo cover
Suppression sizes?
- Peripheral - Central - Foveal
Anti-suppression target sequence?
- Peripheral with little detail - Peripheral with central detail - Central with little detail - Central with foveal detail - Foveal with little detail - Foveal with detail
What does it mean to ADD optical penalization to atropine?
- Pharmacological + optical penalization - If eye is corrected for distance, atropine causes blur at near only - Hyperopic patients - atropine + plano in the sound eye (uncorrected hyperopia) - Want blur at distance and near
Testing EOMs?
- Physiological H pattern isolates muscles and muscle pairs by moving eyes into each diagnostic action field - Test primary up and downgaze - a and v patterns
What is Maxwell's spot?
- Pink spot seen at the macular when viewing a purple background - Macular pigment selectively absorbs blue light - Use this to diagnose/quantify EF
Total occlusion patches?
- Pirate patches - Clip-on patches - Adhesive patches (can be painful) - Slip-on patches (harder to cheat)
Dichoptic stimulus by Hess?
- Play a game - Hess Falling Blocks - Full contrast to amblyopic eye - Reduced contrast to the sound eye - Contrast to the sound eye increases as the game is played successfully
What can it mean if pt does not have RDS?
- Poor motor fusion - Central/foveal suppression
Treating infantile ET?
- Poor prognosis for normal BV - Surgical candidate - Goal is good cosmesis and peripheral fusion
Infantile ET and sensory fusion?
- Poor sensory fusion - Poor prognosis for normal binocularity = goal is often good cosmesis with peripheral fusion
What is a tenectomy?
- Portion of the tendon is excised - Weakens action - SO
What can make you look more exophoric?
- Positive angle Kappa - Narrow bridge of nose - Large PD - Narrow face
What can make you look less esophoric?
- Positive angle Kappa - Narrow bridge of nose - Large PD - Narrow face
How do you stack prisms?
- Power of stacked lenses is higher than the addition of the powers - As power increases, error increases - Large loose prism in front of each eye - Stack horizontal and vertical is OKAY
What are the three components of the critical period?
- Pre-critical period - Critical period - Closure of the critical period
Risk factors for strabismus?
- Premature/low birth weight - Maternal smoking during pregnancy - Hyperopia (ET) - Anisometropia and astigmatism (XT) - Family hx - Neurological and CNS conditions: CP, Downs
Secondary vertical deviation?
- Present only when eyes are deviated (strabismic) - Common in XTs
Three forms of microtropia?
- Primary constant: same size during life - Primary decompensating: gets worse - Consecutive microtropia: Following correction of larger angle strabismus
Uses for botox?
- Primary treatment - After surgery - Acute onset strabismus
What do you need to R/O with unstable sensory fusion in-instrument?
- Primary vertical - Non comitant deviation - Aniseikonia - May occur in TBI patients
Types of vertical deviations?
- Primary vertical deviation - Secondary vertical deviation - Variable vertical deviation - Dissociated vertical deviation
How do you evaluate correspondence in young children?
- Prism adaptation test - Progressive prism adaptation test - if positive PAT
Tests we use to determine how strong is the Anomalous motor fusion response?
- Prism adaptation test - Progressive prism adaptation test
Percentage criteria?
- Prism based on dissociated measure - Percentage of the total dissociated deviation given - May be 1/3 to as high as 2/3
Near cover test and prism measurement?
- Prism is calibrated for minimum deviation position - As prism rotates, the power changes - Minimize frontal plane position: may need to rotate inward for near cover test
Treating esotropia overview?
- Prognosis depends on history, age, type, treatment, and desired outcome - More likely to have amblyopia, AC, and Suppression - Don't eliminate AC/suppression unless you can establish fusion - Your goal isn't always normal binocular vision
AC treatment prior surgery?
- Prognosis lowers with increased number of surgeries - AC in consecutive strabismus is more challenging to treat - If cosmesis is acceptable: usually don't treat - Diplopia or poor cosmesis - may treat
How do you do Bruckner?
- Pt fixates at ophthalmoscope light at about 1 m - Light illuminates both eyes - Observe both reflexes - Brighter reflex = deviating eye - Easier to observe in younger pts
Hirschberg procedure?
- Pt fixates on transilluminator at 50 cm - Evaluate relative distance of corneal reflex from center of the pupil - Compare results to Angle Kappa Temporal is negative and nasal is positive
Possible responses with the major amblyoscope?
- Pt sees two targets but is unable to superimpose - As targets approach each other, they slide or jump past - Central suppression - one target briefly disappears - Horror Fusionis - target jumps to the other side
Side effects of botox?
- Ptosis - Overcorrection - Vertical deviation
Patients for the levodopa for residual amblyopia study?
- Pts b/w 7 and 12 - All had been patching for 2 hours a day > 3 months with a plateau in VA for the last 6 weeks - VA range from 20/50 to 20/400
Features of malingering that psychogenic does not have?
- Purposeful - False or grossly exaggerated symptoms for some benefit - Different in kids vs adults
What do the Haidinger's Brushes look like?
- Radiating lines that resemble a propeller - Only seen at the macula
Treatment arms of IXT2?
- Randomized to observation or patching 3 hours/day - Patch one eye or alternately patch
Constant small angle or micro XT?
- Rare - Can be associated with: post sx, pathology, amblyopia, vertical deviation, and anisometropia - Always rule-out other causes of a small angle constant XT
Features of cyclic esotropia?
- Rare - ET follows circadian rhythm - 24 hours: normal BV - 24 hours: ET - R/O neurologic
Recent onset noncomitant deviation adult symptoms?
- Recent onset of diplopia - Discomfort
What are the surgical techniques?
- Recession - Resection - Myectomy - Tenotomy - Marginal Myotomy - Posterior fixation suture
How does the examiner record Hess Lancaster?
- Record deviation in each DAF - Connect all 8 peripheral DAFs - Compare the enclosures for each eye fixating
Results: How stable is the VA in patients 7-12 years old?
- Recurrence counted as worsening ≥ 2 lines - Probability of recurrence - 7%
Risk of amblyopia recurrence after cessation of treatment?
- Recurrence means 2 or more line reduction of FA - 24% overall recurrence (most by 24 weeks) - Recurrence more common (4x) when patients patched 6-8 hours per day and stopped abruptly Weaning is beneficial
Monocular sensory deficits include which functional consequences?
- Reduced optotype VA - Reduced contrast sensitivity - Reduced spatial localization
Sub-classifications of accommodative ET?
- Refractive - Partially refractive - Non-refractive
Clinical implications of the ATS 13?
- Refractive correction alone improves VA in patients with anisometropic and strabismic amblyopia - Amblyopia can be resolved with spectacle correction alone - some patients won't need occlusion - Correct patients and allow VA to improve before beginning additional treatment (patching)
Types of amblyopia?
- Refractive: anisometropic and isoametropic - Strabismic - Form deprivation
Patient reports on maddox rod/red lens test?
- Report direction of diplopia - Report crossed or uncrossed - The direction of the target is perceived opposite of the direction of the deviation (which is farther away) - Ask pt to report how far apart the targets are
What is Brown's Syndrome?
- Restricted elevation of adducted eye - More commonly unilateral (10% bilateral) - Usually binocular in primary gaze
Etiology of Brown's Syndrome?
- Restriction of the SO tendon at the pulley - Congenital, trauma, or inflammation of the SO tendon
What does a paretic RSR look like on red lens test if it is placed over OD?
- Right field of gaze has the largest separation - Red dot furthest away
What is the Macular Integrity Tester?
- Rotating polarizer - Blue filter makes the HB easier to see
Establishing initial optical Rx?
- Rx lenses that correct RE and decrease size of ET - How much plus: push plus at distance, depending on age - Plus add at near? - Prism? want normal sensory fusion
Plus at near for convergence excess esotropia?
- Rx plus add at near - Calculated AC/A ratio - Cover testing at near with different adds - +3.00 D if very young and difficult to measure
Prism adaptation test?
- Rx resulting in ortho/slight exo over fixating eye - Pt wears for 30-45 mins - Re-evaluate CT - Negative PAT = Ortho/Slight exo - Positive PAT = Eso (suggests AC)
Sensory fusion and suppression checks?
- Seen by each eye: if both seen, no suppression exists - Peripheral, central, foveal locations to provide feedback
Why is taking acuity in amblyopic patients difficult?
- Sensitivity to contour interactions - Abnormal spatial distortion - Unsteady fixation - Poor tracking
What do we want to look at with sensory and motor fusion?
- Sensory fusion present ANYWHERE? In or out of instrument? - Motor fusion present ANYWHERE? Centration point? Start where fusion may be present and move to where it is absent
Sensory stimulation?
- Sensory re-education of visual direction - Large detail-less targets set at objective angle - Alternate flash - Full time occlusion between sessions
Treatment approaches for AC?
- Sensory stimulation - active therapy - Motor stimulation - active therapy - Overcorrecting prism - passive therapy
Eliminating AC in a constant ET?
- Sensory stimulation at the objective angle if it is over 15-20 pd - Motor stimulation if ET is under 15-20 pd - Overcorrecting prism for any size ET
What is combined sensorimotor stimulation?
- Sensory stimulation with first, second, and third degree peripheral/central targets at objective angle - Motor stimulation with second or third degree central/foveal targets at subjective angle - Sensorimotor stimulation with second degree foveal targets
VT sensory and motor fusion?
- Sensory: target content - Motor: target placement VT instruments allow us to alter these two aspects separately to evaluate and train both aspects
Instrument types that present separate targets to each eye?
- Septums - Mirrors - Polaroid/anaglyphic systems - Orthophoric/chiastopic
Results of dark reared cat?
- Shift in ocular dominance columns towards the non-deprived eye - The critical period has been delayed. It only begins when the animals are first brought into light!
ACT and far fixation distance?
- Short rooms will decrease the magnitude of XT - Increase magnitude of ET: esp if high AC/A
How much minus do I use when overminusing?
- Significant amount of added minus - Methods of prescribing: AC/A ratio, CA/C ratio, and trial frame overminus
What do you see with unstable sensory fusion in-instrument?
- Simultaneous perception of targets, but cannot establish fusion - Potentially poor prognostic sign
What is the simultaneous prism cover test (SPCT)?
- Simultaneous place prism over the deviated eye as you cover the fixating eye - Add prism until there is no movement
How do you do contrast sensitivity function testing?
- Sine-wave gratings in a forced-choice test design - The graph plotted by the highest-numbered grating that the patient can see at each spatial frequency - May show gains before VA during therapy
Amblyopia treatment studies visual acuity protocol?
- Single optotype surrounding by crowding bars - Increases sensitivity for amblyopia - Level is passed when child gets 3 out of 3 or 3 out of 4 correct - Continue until child fails a level - Reinforcement phase
Features of intermittent XT?
- Size of angle is often large - Pts often have good sensory fusion despite large angle of strabismus - Always check RDS on these pts, even if looks constant
How do we extend normal SMF to free-space?
- Size of deviation is important: ETs over 15 pd are very difficult to control - Is BV present in open space at any distance? - What size is the deviation at different distances? - Can BV be stabilized with prism? - If the deviation is controlled, does the patient have BV?
What is the definition of a microtropia?
- Small angle strabismus is usually associated with HAC (amblyopia)
Adding a plano lens to atropine treatment for residual amblyopia?
- Small sample size - May be a small benefit to augmenting atropine in patients with residual amblyopia
AC treatment and size?
- Smaller the angle of anomaly = more difficult to treat - Often do not treat small angle strabs (microtropia) with small angles of AC
Correction of refractive error with the ATS 13?
- Spectacles based on cycloplegic refraction - Full correction of anisometropia and astigmatism - Undercorrection of hyperopia ≤ 0.50D - Bifocals for ET that is greater at near than distance
What are some of the features of a monocular VA in amblyopia?
- Speed of response is slow and irregular - Some letters correct and some missed over a large range - Letters read out of order or skipped - Acuity is better with isolated letters - Letters near edge are more accurately read - Potentially poor repeatability
Presurgical normal sensory fusion to establish?
- Stable second degree fusion - Eliminate suppression - Highest level of stereo
What does it mean if a patient second degree targets at the objective angle?
- Stable sensory fusion and no suppression - Great prognostic sign: eliminate motor deviation, good capacity for normal sensory processing - Evaluate with central and foveal targets
Prognosis of a primary vertical deviation?
- Status of BV in non-affected gazes - Size of deviation in affected gazes - Difference in angle size between smallest and largest deviations
For a diagnosis of microtropia, you need to evaluate?
- Stereo (RDS) - Monocular fixation - Cover test - Correspondence
Microtropia magnitude?
0-5 pd
With Haidinger's Brush, what does a left eye nasal EF look like?
0.5 PD here
With Haidinger's Brush, what does a right eye nasal EF look like?
0.5 PD here
Small primary vertical deviation?
0.5 to 5 pd
Which layers of the LGN are parvocellular?
3 to 6
Non-accommodative ET onset?
3-6 years of age
Why do the strabismic amblyopes do worse with crowding?
Actual center of fixation of the amblyopic eye with the highest retinal resolution is displaced. There's a long integration field and signal propagation because the eye is always moving = spatial crowding
After you correct refractive error, and VA plateaus, what do you do?
Add occlusion therapy and follow-up every 6 weeks until no improvement for 2 subsequent visits
Actions of the MR?
Adduction
Main factors that affect treatment according to Flom?
Direction of strabismus, frequency of strabismus, and status of correspondence
What is third degree sensory fusion?
Disparate similar contours
Cells sensitive to ________ are formed in the crucial period
Disparity
Maculo-Macula Test of Cupper: deviating eye?
Examiner projects the visuoscope target centered on the fovea
HBAIT Patient has a 40 CRET with normal fixation What do you expect to see on HBAIT if pt has PACII (subjective 50 ET)
Exception to the rule
If on maddox, the right image is intorted?
Excyclotorsion
Which direction is more favorable for prognosis?
Exo more favorable than eso
Prescribing for anisometropia + esotropia?
Full correction
Prescribing for anisometropia + exotropia?
Full correction
Prescribing for astigmatism + exotropia?
Full correction
Prescribing for esotropia + astigmatism?
Full correction
What type? CT (sc) ortho at D, 25 CAET at N Wet: Plano OU CT w/+2.50 ortho at near
Fully accommodative - non-refractive convergence excess
What type? CT (sc) 20 CAET at D and N Wet ret +5.50 OU CT (cc) 2 EP at D and N
Fully accommodative - refractive Can have phoria left over, give full cyclo sometimes
With correcting refractive error in amblyopia, when would you give the full Rx?
Fully correct myopia, astigmatism, and anisometropia
What is relative amblyopia?
Functional amblyopia can co-exist with disease conditions
Cortical plasticity may be associated with a marked reduction of the ________ pathway
GABAergic
Generally, what is the magnitude of EF?
Generally small (3 PD or less)
What is dichoptic training with binocular summation?
Give a louder, cleaner signal to the amblyopic eye when both are open and see what happens with summation
What is VEP?
Indirect measure of infant vision.
DVDs are commonly associated with?
Infantile strabismus - infantile ET, 70% of infantile ETs have a DVD
Amblyogenic refractive risk factors for astigmatism?
Isoametropic: ≥ 2.50 D Anisometropic: ≥ 1.50 D
Amblyogenic refractive risk factors for myopia?
Isoametropic: ≥ 6.0 D Anisometropic: ≥ 3.0 D
What do you need to R/o with a vertical strabismus?
Isolated paretic cyclovertical muscle
Amblyogenic refractive risk factors for hyperopia?
Isometropic: ≥ 4.0 D Anisometropic: ≥ 1.0 D
Describe what change happens at the synaptic level when there are two monocular LGN axons firing onto the same cortical neuron in V1 in an untreated unilateral amblyope -- in the amblyopic side
LGN axon that is unable to stimulate the cortical neuron with excitatory transmission will start to reduce the number of neurotransmitters available inside its synaptic terminal. Synapse will begin to atrophy
Which onset is more favorable for prognosis?
Later onset, over 1 year, is more favorable
What is LTP?
Long term potentiation is persistent strengthening of the synapse based on recent patterns of activity
The increase in the ratio of NR2b to NR2a observed in visually deprived adults is predicted to?
Lower the threshold for activity-dependent synaptic potentiation, consistent with the rapid potentiation observed in response to stimulation of the non deprived eye
What are reverse suturing studies?
MD an eye of the animal, then open this eye and reverse occlude the eye that was initially not monocularly deprived. Note at what age the ocular dominance columns in the initial MD eye respond.
At rest, NMDA receptor is blocked by?
Mg 2+
Intense depolarization removes ________ and with synchronized activity, the NMDA channel is ________
Mg 2+ Opened
Where do we set bifocals for a kid under 5?
Mid-pupil
With age, peak sensitivity shifts towards __________ spatial frequency
Middle
What type? CT (sc) 20 CRET @D, 40 CRET @ N Wet Ret: +2.50 OU CT (cc) Ortho @ D, 20 CRET @ N CT with +2.50 add ortho @ near
Mixed refractive, non-refractive
Ocular dominance columns 2, 3, 5, and 6?
Mixture of cells from both eyes
PEDIG - ATS 2A study population?
Moderate amblyopes (VA 20/40 to 20/80) in children younger than 7 years old
The critical period in animal models can be ________ with visual experience
Modified
What is a myotomy?
Muscle is incised or completely transected
What is a marginal myotomy?
Muscle is weakened by reducing the number of contractile elements without changing the contact with the globe
After NC is achieved with sensory simulation, what must happen?
Must decrease the angle of deviation so the patient can be binocular in free space
Bagolini, patient reports crossed diplopia, neutralize, and no movement on UCT?
NC
Bagolini, patient reports uncrossed diplopia, neutralize, and no movement on UCT?
NC
Cover test 20 CRET Bagolini uncrossed that neutralizes with 20 BO No movement on UCT after What type of correspondence?
NC
Deviation caused by non-registered eye movements?
NC
Worth 4 dot: diplopia, neutralize, UCT no movement?
NC
Which comitancy is more favorable for prognosis?
NC is more favorable than AC
The potential for neuroplasticity __________ stops
NEVER
The activation of the ____________ is a key mechanism of developmental neural plasticity
NMDA receptor
Does the magnitude of the strabismus deviation relate to the severity of the amblyopia?
NO: As long as it is a constant, unilateral strab, there will be amblyopia. Higher magnitude won't make the amblyopia worse
Visual deprivation from dark rearing in juveniles prevents ___________ from binding to ___________
NR2a NMDA
More ___________ NMDA subunit = more plastic
NR2b
The correlation between high levels of ________ containing NMDARs and a low threshold for long term potentiation has also been demonstrated after learning novel information
NR2b
The NMDA receptor has what two components?
NR2b and Nr2a subunits
If you have esotropia, which type of EF is most common?
Nasal EF
Recent onset vertical deviation?
Need a neurological eval
What does it mean that the LGN is topographically organized?
Neighboring parts of the retina project to the neighboring parts of the nucleus creating a map of the field of view
LGN is responsible for __________ perception
Object
What motor fusion ranges do we work on?
Objective angle and orthoposition
Etiology of A and V patterns?
Oblique dysfunction
Full time reverse occlusion in monocularly deprived kittens led to _______ in the previously open eye
Occlusion amblyopia
What is it called when full time patching causes a reduction in VA on the good eye?
Occlusion amblyopia
What is inverse occlusion?
Occlusion of the amblyopic eye
Passive therapy?
Occlusion: - Used in treatment of IXT - Amblyopi
CN III innervates?
Oculomotor nerve SR, IR, MR, and IO
Cover test 20 CRET Bagolini crossed that neutralizes with 5 BI Movement on UCT after What type of correspondence?
PAC 1 Subjective is saying exo Cover is saying eso
Patient subjective angle is 10 XT and the cover test is 20 ET. What is this?
PAC I - Angle of anomaly is greater than the objective
Cover test 20 CRET Bagolini uncrossed that neutralizes with 30 BO Movement on UCT after What type of correspondence?
PAC II Objective 20, Subjective 30
Patient subjective angle is 30 XT and the cover test is 20 XT. What is this?
PAC II - Subjective exceeds objective
Forced duction and Brown's?
POSITIVE Forced Duction
What happens with ZRMV and PVD with eccentric viewing?
PVD > fovea and ZRMV > EV location - No eccentric localization - Associated with ocular disease conditions - Consciously move vision over
When contrast sensitivity develops, what allows for the increased sensitivity at high spatial frequencies?
Packing of foveal cones closer together
For amblyopia treatment we employ _________ in optometric clinical practices
Part time occlusion therapy
What can we do to tell the difference between congenital torticollis vs ocular torticollis?
Patch one eye, if straighten = ocular, if no movement = congenital Patch test
From Wu and Hunter: The traditional amblyopia therapy consists in?
Patching or penalizing the fellow preferred eye, thus forcing the brain to use the visual input carried by the amblyopic eye
What did ATS 2 look at?
Patching time for moderate amblyopia
UCT and eccentric fixation?
Can contaminate results: - Size of movement - Type of movement
If you have greater eso at near, the AC/A will be _______ than IPD
Greater
With amblyopic patients, how does EF's effect on VA change?
Greater decreased in eccentric VA than normals
Which eye can see the grid if its a white background with red lines?
Green eye - that's why it is the fixating eye Do not want the testing eye to know where the circles are or have any hints on where they should be
With an anisometropic patient, there is more pronounced loss at _____ spatial frequencies when compared to normal eyes
High
What is the initial step in treating amblyopia?
Correcting refractive error
Types of prism?
Corrective prism, relieving prism, over-corrective prism, inverse prism, yoked prism, and sector prism
You should evaluate _____ before beginning anti-suppression therapy
Correspondence
_________ is probably the single most important thing for strabismus treatment in determining success and length of time
Correspondence
Why evaluate correspondence?
Correspondence will have the largest impact on prognosis and management
BDNF promotes maturation of __________________ during early mouse's life = begins critical period for visual cortical plasticity
Cortical GABA pathway
Why should I treat Strabismus?
Cosmesis, improve symptoms, stereopsis, expand occupational opportunities, provide good patient care, and its rewarding for the clinician and patient
Cover test 25 BI Subjective 30 BI 5 pd temporal EF?
Cover changes to 30 Subjective still 30 NC
Cover test 25 BO 5 nasal EF Subjective 40 BO What is the angle of anomaly? Will you see movement on Douse?
Cover is really 30 Subjective > cover test PAC II Yes - move in, negative
BDNF availability is linked to?
Critical period onset and closure and indicated that neither of these are fixed times
Macaque critical period?
Critical period starts at 1 month old, eyes open at birth
Why is it important to test sensory and motor fusion?
Critical to develop a management plan: What treatment options we can use and where in the treatment sequence we begin
Common AC response in ET with HBAIT?
Crossed - different than diplopia!
The visual system is more plastic and remains more plastic for a longer period of tie at?
Higher processing levels
When may suppression occur?
In strabismus and heterophoria
Amblyopia is?
Decreased vision in one or both eyes due to abnormal development of vision in infancy or childhood
If you increase the EF's distance from the fovea, what happens to VA?
Decreases
What is binocular therapy for amblyopia aimed at?
Decreasing suppression and promoting fusion
What is strabismus?
Deficit of muscular control of the eyes leading to a tropia
The Pattern of Visual Deficits in Amblyopia study conclusions for anisometropic amblyopes?
Deficits in optotype and vernier acuity were nearly proportional to the deficit in grating acuity
Darking rearing has shown to _____________ the onset of the critical period in adult rats and cats, proving that __________ is necessary to trigger the events of ocular dominance
Delay Visual experience
Prognosis of partially accommodative ET?
Depends on what we are after: cometic? Normal BV?
Result of brief monocular deprivation for 3 days in a juvenile rat?
Depressed neural response in MD eye and shift in ocular dominance towards the open eye
What is suppression intensity?
Depth of suppression - under what conditions does the suppression exist? Natural or unnatural?
Goal of ATS - 7?
Determine the amount and time course of binocular VA improvement during the treatment of bilateral refractive amblyopia in children 3 to under 10 years old
In a normal eye, what determines contrast sensitivity?
Determined by cone length and width and their ability to catch photons
What is the crucial period?
Development of binocular vision, 3-5 months for humans
Central suppression size?
Diameters greater than 1 degree or 2 pd, but less than 5 degrees or 10 pd
Peripheral suppression size?
Diameters greater than 5 degrees or 10 PD
Foveal suppression zone?
Diameters less than 1 degree or 2 pd
How do we achieve the benefits of binocular therapy for amblyopia?
Dichoptic stimulus
Primary outcome of IXT2?
Did the patient reach deterioration? - CXT - Loss of near stereo by 2 octaves - Use of any non-randomized treatment
Testing methods for evaluating ocular deviation?
Direct observation, Hirschberg test, Krimsky test, Bruckner test, Unilateral cover test, and alternate cover test
Instruments with septums?
Brewster Stereoscope
With Pratt-Johnson, there is no hemiretinal suppression but a?
Hemiretinal trigger for suppression - Nasal retina of ET or temporal retina of XT Hemiretinal diplopia trigger when image is on opposite side - Temporal retina of ET or nasal retina of XT
Prism therapy for primary vertical deviation?
Prism amount: - Tolerance to primary vertical is variable - RVD criteria: 2-4 pd residual vergence - May need corrective prism - Determine dissociated and associated deviation (in all fields of gaze if non comitant) - May need different prism amounts in different fields of gaze if non-comitant
What is sensory fusion?
Process by which stimuli seen separately by two eyes are combined, synthesized, or integrated into a unitary percept
_____________ is very important in the treatment of strabismus
Prognosis
Treatment goals depend on?
Prognosis, patient complaints, patient goals, and other factors
Consider testing ________ at distance as well as near with IXTs
Randot stereo
Diplopia and OAIO?
Rare
How often does form degradation happen?
Rare, occurs in 0.1% of the population
With what form of amblyopia is eccentric fixation least likely?
Rarely in anisometropic amblyopia
Implementing plus at near?
Reading glasses, bifocals, PALs
If the suspect is malingering, what do you need to rule out?
Refractive causes and ocular pathology
For a diagnosis of microtropia, you need to rule out?
Refractive error and ocular pathology
Etiology of amblyopia?
Refractive, strabismic, form degradation, and image deprivation
Cover test: 10 CRET Pt notes red and white are aligned What is subjective angle? What type of correspondence?
Subjective = 0 HAC
What does double maddox measure?
Subjective test to measure torsion or cyclodeviation - Do on pts with head tilt or tilted images - CN IV PARESIS
Unilateral suppression?
Same eye is always suppressed
Efficiency of synaptic transmission is increased when?
Subsets of presynaptic inputs are correlated
Presynaptic inputs are lessened when?
Subsets of presynaptic inputs are persistently uncorrelated
What does it mean if HB and AI are not aligned, and HB is not at the fixation point?
Suggests AC AND EF
What does it mean if HB and AI are not aligned, but HB is at the fixation point?
Suggests AC but no EF
What does it mean if HB and AI are aligned, but displaced from the fixation point?
Suggests NC and EF
What does it mean if the fixation point, HB, and AI are all in the same location?
Suggests NC and NO EF
What does it mean that a suppression is deep?
Suppression present under most or all conditions
Two or three dots on worth 4?
Suppression!
The Hebbian model suggests that the __________ is the neuronal location where plasticity changes occur
Synapse
____________________ causes the strabismic amblyopia eye to make false judgements about positional locations of objects in space
Spatial aliasing
What is the biggest risk factor for esotropia?
Spherical equivalent RE >= +5.00
Subjective compliance of 2 hours of patching vs 6 hours of patching?
T2 hours reported much better compliance than 6 hours
T/F: In the Hebbian theory, if one of the LGN connections is weakened or lost, the cortical neuron will no longer be binocular
TRUE
T/F: The depth of the suppression does not correlate with the size of suppression zone
TRUE
T/F: The physiological properties of the LGN cells that were driven by the sutured eye were grossly normal
TRUE
T/F: The retina tissue in the sutured eye was normal
TRUE
T/F: Position of the eyes do not matter with HBAIT
TRUE not dependent on eye position
Polaroid/anaglyphic systems?
TV trainer and Vectograms
What do you do when you reach maximum VA?
Taper treatment then monitor
Is major amblyoscope distance or near?
Technically distance
If you have exotropia, which type of EF is least common?
Temporal EF
Method for The Pattern of Visual Deficits in Amblyopia study?
Testing grating acuity, vernier acuity, optotype acuity, contrast sensitivity, and edge contrast, as well as binocular integration and stereo
Describe what change happens at the synaptic level when there are two monocular LGN axons firing onto the same cortical neuron in V1 in an untreated unilateral amblyope -- in the nonamblyopic side
The LGN axon that has a strong connection will continue to stimulate the cortical neuron and that synapse will be strengthened
What is a vernier hyperacuity?
The ability to detect a misalignment of two lines
What is contrast sensitivity?
The ability to detect, discriminate, or recognize objects that vary slightly in relative luminance
Because of the size increase of Panum's area with peripheral vs central, what does this allow for?
The ability to obtain peripheral fusion without central/foveal fusion
With HBAIT, if the horizontal line is centered at a fixation point, and the vertical line is so many cms away, what does this tell us?
The angle of anomaly = 1cm @ 1m = 1 pd
What is the angle of anomaly?
The angular separation between the fovea of the deviating eye and a point in the eye which corresponds to the fovea of the fixating eye (point a)
With the assessment of visual acuity, it is important to identify what?
The best corrected visual acuity in each eye
What does the 4 BO test evaluate for?
The presence of a small central suppression scotoma
The major changes that occured in the sutured cat were in where?
The projections from the LGN to the visual cortex
What target details do we start with if patients have good sensory fusion?
Start with targets that have more detail
What target detail do we start with if patients have poor sensory fusion?
Start with targets that have very little detail
Cats critical period?
Starts at 3 weeks of age after eyes are open
Human critical period?
Starts at birth, heightens at 1-2 years old, then diminishes and plateaus at age 7 to 8
______________ is the ability to perceive depth arising from resolvable disparity between two images
Stereopsis
What is congenital torticollis?
Sternocleidomastoid muscle fibrosis -- tightened or shortened
Bonneh et al research demonstrated that _________ amblyopes perform worse on both temporal and spatial crowding tasks
Strabismic
Levi and Klein demonstrated what with vernier acuity?
Strabismic amblyopes have much poorer vernier acuity compared to anisometropic amblyopes. Much poorer than predicted by their grating acuity.
The Pattern of Visual Deficits in Amblyopia study conclusions with binocular testing?
Strabismics did worse on both randot and BIM motion test than anisometropes
With Hess Lancaster, the direction of the deviated eye's target is projected in?
The same direction as the deviation
Blakemore and Van Sluyters (1974) study: Kittens with monocular occlusion at birth for 5 weeks?
The sound eye's ocular dominance is noted in as little as 3 days
Sensory signals carried from the eye to the brain have a dramatic effect on?
The structure and physiological properties of the brain
Which parts of the brain remain plastic in adults?
The temporal cortex, which stores visual memories, and the hippocampus
Shallow or no amblyopia and suppression?
Strongest suppression in patients with strabismus
The GABA pathways establish?
The visual critical period - starting gate
What is blind spot syndrome?
Theoretical - Optic nerve of the deviated eye is used as a suppression zone - No sensory adaptations - Good potential for sensory fusion
Astigmatism and anisometropia only lead to amblyopia if?
They persist more than two years
What happens when a patient has normal correspondence and is strabismic?
They will either suppress or experience diplopia when strabismic
Problem with sensory stimulation?
Time intensive, patient must be very complaint - 3-5 days per week for 20 to 25 minutes - May see NC response in 4-6 months - Full time occlusion when not undergoing sensory stimulation
Degree of vision loss with deprivation amblyopia depends on?
Time of onset and degree of obstruction
CN IV innervates?
Trochlear nerve SO
Tropicamide vs cyclopentolate?
Tropicamide peaks at about 20 mins and then drops off quick. Cyclo peak lasts a lot longer with less residual accommodation
T/F BDNF is the on switch for the critical period and can be manipulated in dark rearing studies
True
T/F: Amblyopia occurs in the absence of structural or pathological abnormalities
True
T/F: Despite large angles, global stereo is often very good with IXTs
True
T/F: Duane's is usually congenital
True
T/F: EF is generally in the same direction as strabismus
True
T/F: Even with NC, sensory and motor fusion may be normal or abnormal
True
T/F: Most vertical strabismus is noncomitant
True
T/F: Patients with amblyopia may have peripheral fusion and central suppression
True
T/F: High astigmatism is a large risk factor for extropia
True! Over 2.5 D
T/F: The LGN has plasticity
True: LGN has SOME plasticity
T/F: The primary visual cortex, V1, has plasticity
True: Most plastic out of LGN and Retina
T/F: Hirschberg test does not disrupt the patient's normal binocular status
True: No dissociation
T/F: Eccentric fixation is usually unilateral
True: rarely bilateral
Why is there a greater decrease in eccentric VAs with amblyopes?
Two mechanisms to vision loss: - Sensory - inhibition - Motor - eccentric fixation Sensory vision is already decreased, then the EF adds on top of that already reduced vision
Any ET after _________ is abnormal
Two months
Cover test 20 CRET Bagolini uncrossed that neutralizes with 10 BO Movement on UCT after What type of correspondence?
UHAC Subjective less than objective but greater than zero
What can you do with ACT if they have latent nystagmus?
Use a frosted occluded or high plus lens
Purpose of the levodopa for residual amblyopia study?
Use of levodopa may improve residual amblyopia in children age 7-12
What is eccentric fixation?
Using an extrafoveal point when fixating monocularly
What are the kinds of A and V patterns strabismus?
V-eso (most common) A-eso V-exo A-exo (least common) X or Y patterns are rare
Results over 5 weeks?
VA continued to improve in 48% of patients
Results of ATS 13?
VA improvement was NOT related to eye alignment
Active strabismus treatment?
Vision therapy/orthoptics
The _____________ is the first location where signals from the two eyes converge onto a single cell
Visual Cortex (V1)
Measures of crowding are highly correlated across subjects while being independent of?
Visual acuity
Primary outcome of the study?
Visual acuity: - Standardized, masked VA testing - Single, surround HOTV
Sensory fusion peripheral target size?
Visual angle over 10 pd - beyond macula
Sensory fusion and foveal target size?
Visual angle under 10 pd - fovea
Reduced GABAergic pathway = facilitates __________________
Visual cortex plasticity regulation
Objective evaluation of EF?
Visuoscopy
What is the most common method for evaluating EF?
Visuoscopy
Why do strabismics have better contrast?
We assume that each retinal signal provides one unit of excitation and each cortical cell receives two of these signals. Each monocular cell gets two from its preferred eye and each binocular gets one from each eye. In strabismics, THEY DON'T have binocularity. so
Treatment of severe amblyopes?
We patch the sound eye 6 hours a day with 1 hour of near work and monitor visual improvement at 6-8 week intervals
Strabismic anisometropic zone of the amblyopia map?
Western zone has very poor acuity and normal or subnormal sensitivity
UAC in XT vs ET?
XT - b/w f+Z, temporal to fovea EP - b/w F+Z, nasal to fovea
Score 3?
XT <50% of the time before dissociation
Score 4?
XT > 50% of the time before dissociation
HAC in XT vs ET?
XT: Temporal to fovea ET: Nasal to fovea
Don't eliminate suppression unless?
YOU CAN OBTAIN GOOD SENSORY FUSION
Should EOG and ERG be normal in amblyopia?
Yes!
At high spatial frequencies, can you see the stripes?
You cannot see the stripes no matter how high the contrast
Don't eliminate AC or suppression unless?
Your patient can complete treatment program: If you break suppression, can you establish fusion? If you break AC, can you establish fusion?
Normal observers and binocular sumation?
1.4 - 1.8 x improvement
Deeper amblyopia and suppression?
Less suppression in patients with strabismus
How much strabismus is not cosmetically noticeable?
Less than 10 pd
Head posture with Paretic vs Non-Paretic strab?
P: Abnormal NP: Usually normal
Age of onset Paretic vs Non-Paretic strab?
P: Any age NP: During childhood
Hx of head trauma with Paretic vs Non-Paretic strab?
P: Common NP: Uncommon
Diplopia with Paretic vs Non-Paretic strab?
P: Common NP: Uncommon
Onset of Paretic vs Non-Paretic strab?
P: Sudden NP: Gradual
Recent strab?
- (+) Diplopia - Noncomitant - No amblyopia - Marked abnormal head position
Results - mean baseline VA?
- +4.00 to +7.00 = 20/63 - +7.00 = 20/100
How do we taper atropine?
- 1 drop per week x 6 weeks - Stop - F/u after 6 weeks
Post-Op Eval?
- 1 to 2 weeks after surgery - 6 weeks, healing is complete - Direction, frequency, and magnitude of deviation: over correction is common - Test sensory and motor fusion - Will lenses help? Therapy if indicated
Results: ATS 18 binocular treatment vs patching in 13-16 year olds
- 13% of the patients in the binocular game playgroup had a compliance of > 75% - iPad game was not found to be better than patching
Adult amblyopia treatment with VR games on oculus rift?
- 17 adults - Anisometropic amblyopia - 8 - 40 min training sessions - Significant VA and stereo improvement
Treatment arms of the ATS 2 for moderate amblyopia?
- 2 hours of daily patching + 1 hour near activities, 5 week f/u, 17 week f/u - 6 hours of daily patching + 1 hour near activities, 5 week f/u, 17 week f/u
PEDIG - ATS 2A was comparing?
- 2 hours of daily patching with one hour of near work - 6 hours of daily patching with one hour of near work
Video gameplay amblyopia treatment in adults?
- 20 adults with amblyopia - Played action or non-action video games - Crossover control (20 hours occlusion; 40 hours of games) - Improvement in VA and stereo that cannot be explained by patching alone
Subject requirements for the ATS-7?
- 20/40 to 20/400 BCVA - Hyperopia ≥ 4.00D and/or astigmatism in each eye ≥ 2.00D
Results: ATS 18 binocular treatment vs patching in 5 to 12 yr olds
- 22% of the patients in the binocular game playgroup had a compliance of 75% - VA improved with both treatments - non-inferiority analysis was indeterminate - analysis says VA improvement with iPad is not as good as patching
Watching movies to treat amblyopia study: Li et al.
- 3 movies/week for 2 weeks - 2 lines of improvement in acuity, no improvement in stereo or suppression
Quantifying severity on versions?
- 4+ = severe OA to 4- = severe UA Each # = 25% so +2 is 50% OA
Treatment arms of the ATS 2 for severe amblyopia?
- 6 hours of daily patching + 1 hour of near activities, 5 week f/u, 17 week f/u - Full time patching + 1 hour of near activities, 5 week f/u, 17 week f/u
About how long does atropine last?
- 7 days or longer - Max at 3-6 hours - Side effects more common
Clinical implications of ATS-7?
- 73% of patients with binocular amblyopia achieved 20/25 within one year of treatment with spectacles - Improved acuity = improved stereo
Results of IXT3?
- 8 weeks mean distance control was significantly better in the overminus group - Side effects (headache, asthenopia) similar between groups
AC in XT vs ET and prognosis?
- AC in XT = good prognosis - AC in ET = very guarded prognosis
What is sensory theory?
- AC is an acquired sensory adaptation - Adaptation of the brain to the strabismus: restores binocularity, although anomalous, by shifting the subjective visual direction of the strabismic eye - NC becomes AC slowly over time: Shallow to deep - As AC becomes embedded, it is more difficult to get NC
R/O what with non-accommodative ET?
- Accommodative ET - Partially accommodative ET - Neurological cause
Accommodative status ET classifications?
- Accommodative ET - Partially accommodative ET - Non-Accommodative ET
Features of partially accommodative ET?
- Accommodative component - Non-accommodative component that remains after full correction of refractive error - More likely to have sensory anomalies
When correcting myopia, what do you need to double check?
- Accommodative demand - support if near problems arise - Change in ocular deviation - recheck cover
Cover test targets?
- Accommodative target - make sure patient keeps the target clear - Have pt read the letter or describe the picture to ensure clarity - If amblyopic, make sure it is within threshold
Advantages of cycloplegic retinoscopy?
- Accomodation controlled - Still have to make sure on axis - Can have pt look directly at light (subtract working distance)
Treatment goals?
- Accurately assess correspondence and sensory fusion - Establish conditions under which sensory fusion can be established - Establish diplopia when eye deviates
With Flom's swing, what should they achieve/improve?
- Achieve co-variation - Improve divergence skills
VT/surgery combo?
- Active VT combined with surgery - Establish normal sensory fusion before surgery - Eliminate suppression and establish fusion before surgery - After surgery, eliminate residual angle, stabilize sensorimotor fusion
Vision therapy for strabismus?
- Active treatment for strabismus - Involves pt consciously in controlled visual tasks - biofeedback important, taught to obtain a response
Why do we develop AC?
- After strabismus develops: diplopia/confusion - We want to eliminate diplopia/confusion so we either suppress or develop AC
The critical period for ocular dominance changes starts ________________ and continues some time near ________
- After the eyes are open - Puberty
General with esotropia?
- Age onset is important - Generally poor sensory fusion - Sensory adaptations is common - Must r/o neurological cause in any sudden onset or atypical ET
Fluoxetine study?
- All subjects were patched and had perceptual VT - No difference between fluoxetine and placebo - Both groups did improve slightly = patching and VT may be helpful in adults
Registered movements and the motor theory?
- Altering egocentric direction - Neural impulses communicate with EOMs and perceptual apparatus in the brain - Changes in correspondence and eye movement Fusional vergence
What are the dissociated vertical deviations?
- Alternating Hyperphoria - Double dissociated hypertropia - Dissociated vertical divergence
Treating amblyopia in older patients summary?
- Amblyopia can be treated in children 7-17 years old - Treatment with patching or atropine produced similar improvement in VA in children 7-12 years old - Recurrence rate of amblyopia in the first year was low
Results of The Pattern of Visual Deficits in Amblyopia study?
- Amblyopia is not a single abnormality that is completely characterized by optotype acuity. - Deviation suggests that there are systematic differences among strabimics, anisometropes, and strabismic anisometropes
What can you work on to improve monocular function?
- Amblyopia? - Fixation - Accommodation - Oculomotor skills Helpful even if sending for surgery
Activities at the angle of deviation?
- Amblyoscope - Activities at the centration point (ET) - Mirror superimposition - Single oblique mirror stereoscope - Vectograms/Tranaglyph
In-instrument sensorimotor evaluation options?
- Amblyoscope - Mirror stereoscope - Brewster stereoscope - VTS 4
How much the non-amblyopic eye is blurred depend on?
- Amount and type of RE - Correction the patient is wearing
Assessing visual efficiency with accommodation?
- Amplitude: push up, pull away, and minus to blur - Accuracy: MEM, Crossed cylinder method (FCC) - Facility: MAF, BAF
How do you get interocular transfer (IOT)?
- An adapting stimulus presented to an eye over a period of time until it fatigues the neural mechanisms responsible for encoding that stimulus - The after effect of the stimulus is transferable to the other eye - Best displayed with the tilt after-effect
Surgical complications?
- Chronic conjunctival inflammation - Scar tissue - Granuloma - Corneal Dellen - Lost/slipped muscle - Globe perforation _endopthalmitis - Anterior seg ischemia - Diplopia - Consecutive strabismus - Complications of anesthesia
How does overminusing work?
- Clear blurred image from pseudomyopia: excessive accommodation by accommodative convergence - Stimulates accommodative convergence: decrease the size of the angle
What is Flom's functional cure?
- Clear, comfortable, and single binocular vision at all distances and at all gazes - Normal NPC - Stereopsis - Normal motor fusion ranges - Intermittent strab up to 1% of the time - Prism up to 5 pd
What is Flom's functional cure?
- Clear, comfortable, and single binocular vision at all distances and in all gazes - Normal NPC - Stereo - Normal motor fusion ranges - Intermittent strab up to 1% of the time - Prism up to 5 pd
Motor stimulation in XT?
- Co-variation occurs with convergence - Fixation at ortho position = NC Therapy techniques at ortho position - Monitor correspondence status with foveal tags - Stabilize BV at ortho position with therapy
What should you do with occlusion therapy?
- Combine with at least one hour of structured near work every day (coloring, mazes, computer games, amblyopia iNet) - F/u every 6 weeks until VA stops improving - Check compliance
Primary vertical deviations?
- Comitant and non-comitant - Controlled by vertical vergence
Clinical features of blind spot syndrome?
- Comitant, constant ET 20-35 at D and N - Blind spot of deviating eye overlying fixation point (z) - No amblyopia - Normal correspondence - Fusion potential - Diplopia when the image is placed out of the blind spot so need continued motor readjustment
What is malingering?
- Common in school-aged children - Chief complaint is usually reduced VA - May have abnormal findings on any subjective test - Inconsistent test results common - Rule-out pathological causes
Near activities while patching clinical implications?
- Common near activities with two hours of daily patching do not improve VA outcomes in patients with anisometropic strabismic or combined mechanism amblyopia - Structured near activities have not been researched
Presentation of psychogenic vision loss?
- Commonly females aged 8-14 years - Binocular decreased VA - Possible history of psychogenic cause - Tubular visual field
Red lens test?
- Compares objective to subjective - Best optical correction - Distance target (penlight) - Step 1: measure objective (ACT) - Step 2: determine subjective: vertical prism and red lens over one eye for diplopia, add prism until alignment - Step 3: compare objective to subjective
What is corrective/neutralizing prism?
- Completely eliminates vergence demand - Corrects for the entire deviation
What is augmented reality?
- Computer generated enhancement over a feed of an existing environment - Patches of video feed can be seen by each eye
What is amblyopia iNet?
- Computer program for amblyopia therapy they can do at home - Can set VA and make it bilateral or unilateral, time - Good for younger kids 5-6 yo
What is anomalous correspondence?
- Condition in which the two foveas do not give rise to a common cortical visual direction - The fovea of one eye is functioning directly with an extrafoveal area of the other eye - Anomalous fusion
Three most common causes of noncomitant deviations in children?
- Congenital - Trauma - Acute viral infection
Do infantile ETs spontaneously resolve?
- Congenital Esotropia Observational Study - 4 to 20 weeks of age with over 20D ET - ET spontaneously resolved in 27% of patients (intermittent, variable angle, or accommodative) - IF it was a constant ET over 40D, after 10 weeks of age it is unlikely to resolve
What typically causes deprivation amblyopia?
- Congenital cataract - Ptosis - Hyphema - Corneal opacity - Vitreal hemorrhage - Prolonged patching or cycloplegia
Amblyopia and congenital vs acquired deviations?
- Congenital: May be present - Acquired: Absent
Suppression and congenital vs acquired deviations?
- Congenital: May be present - Acquired: Absent
Difference between primary and secondary deviation with congenital vs acquired?
- Congenital: Paretic none, mechanical present - Acquired: Present
Limitation in ocular motility with congenital vs acquired deviations?
- Congenital: Paretic not severe, mechanical marked - Acquired: Severe
Clinical implications: Comparing bangerter filters and patching?
- Filters did not meet the "non-inferiority" criteria compared to patching - Filters provided less of a burden to families - Reasonable option for initial therapy for moderate amblyopia
Target content?
- Find target parameters that the patient is able to fuse - Targets are changed throughout therapy to improve sensory fusion
What are adjustable sutures?
- Fine tune alignment postoperatively - During surgery, a slip knot is placed on the muscle - Post-op, cover test can be performed and the angle of deviation can be adjusted by moving the slip knot - Used in older patients
Optical correction as the initial treatment of amblyopia?
- First, correct refractive error in ALL types of amblyopia - F/u schedule every 6 weeks - Follow patients until acuity does not improve on two subsequent visits - consider additional treatment
Ocular motility testing for visual efficiency?
- Fixation - Saccades - Pursuits
Other ways to Rx prism based on associated measure?
- Fixation disparity: Small vergence error within Panum's area - Associated phoria: Amount of prism needed to FD - Wesson Card: AO vectographic slide
Prescribing overminus for IXT?
- Fixed amount of overminus - Fixed amount of overminus above cyclo refractive error - Based on control of deviation/size of angle during single office visit - Based on control of deviation/size of angle during a series of office visits
How do you do Haidinger's Brush + AIT?
- Flash vertical AI to preferred eye - Occlude preferred eye, have nonpreferred eye view Haidinger's Brush - Compare position of the fixation point, HB (fovea of non preferred eye), and AI(tages fovea of preferred eye)
Post-surgery for ET?
- Follow-up - Post-surgical VT
Etiologies for an acute-onset comitant ET?
- Following occlusion (full time patching, don't do often at all) - Post physical, emotional shock, or stress - Idiopathic - Neurological causes
Anomalous correspondence?
- Fovea of the fixating eye and a non foveal site of the deviating eye have a common visual direction - Binocular condition - Cortical phenomenon
More natural to less natural suppression intensity tests?
- Free space - In-instrument - Polaroid filters - Red filter - R/G filter
What impacts prognosis of esotropia?
- Frequency - Magnitude - Comitancy - Age on onset - Age of treatment - Duration of ET - Sensory anomalies
What impacts prognosis in IXT?
- Frequency: start training where intermittent - Magnitude: larger may need surgery - Comitancy: extend therapy into other gazes - Laterality - AC - Suppression: how deep
Prescribing for exotropia and myopia?
- Full amount needed to correct ametropia - Overminus
Results of environmental enrichment and perceptual learning in adult rats?
- Full recovery of ocular dominance - Marked reduction in GABAergic inhibition
PEDIG ATS 2B treatment arms?
- Full time (all hours except 1 hour per day) - 6 hours of daily patching + 1 hour of near work
Different timings of occlusion therapy?
- Full time occlusion - all waking hours - Part time occlusion - less than full time, generally 1-6 hours/day
Corrective lenses should be based on what and correct what?
- Fully correct the ametropia - Base off of a cycloplegic retinoscopy/refraction
Correcting anisometropia?
- Fully correct the anisometropia: equal stimulus to accommodation, better sensory and motor fusion - Cut plus equally from each eye
Correcting anisometropia?
- Fully correcting anisometropia! - Equal stimulus to accommodation = better sensory and motor fusion - Cut plus equally from each eye
Side effects of cycloplegics?
- Hot as a hare - Mad as a hatter - Dry as a bone - Red as a beat - Blind as a bat
How to measure EF magnitude?
- How far from the fovea is the patient fixating - Measured in prism diopters
History of an acute-onset comitant ET?
- How/when first noted? Constant or Intermittent? - Anomalous head position? - Diplopia? - Other systemic or neurological signs?
Psychogenic vision loss is also known as?
- Hysterical Amblyopia - Psychogenic Amblyopia - Non-organic vision loss - Visual conversion reaction
When do you do in instrument motor stimulation for AC?
- IET (if unsuccessful out of instrument) - CET under 15-20 PD - CXT (if unsuccessful out of instrument)
Establishing binocular vision in free space?
- IF angle remains large, may need prism/surgery (over 20 pd) - Stabilize accommodative and vergence skills in open visual space
DDx of Brown'?
- IO paresis - Orbital floor fracture - Thyroid orbitopathy
When do you do out of instrument motor stimulation for AC?
- IXT - IET - CXT
Basics of Hess Lancaster test?
- Identify affected muscle - Determine magnitude of change in each field of gaze - Pt wears red/green glasses - Red + green laser pointer
When/how do you do duction testing?
- If US on version testing - Examine extent of OM limitation - Test monocularly - Move target into DAF
If you are cutting the Rx, what do you need to make sure you do?
- If cutting the Rx, cut the Rx equally based on the cycloplegic refraction - Give the full astigmatic correction
In both cases, deprivation induces an ______________ of the NMDA receptor = __________ in cortical plasticity
- Immature version - Increase
Binocular sensory deficits include which functional consequences?
- Impaired stereopsis - Reduced binocular summation
Overminus as treatment for IXT?
- Improve control in patients too young for other treatment - Passive vergence training - wean off lenses
Active VT?
- Improve sensorimotor fusion - Improve control - Improve awareness of eye position - Decrease asthenopia
Intermittent ET options?
- Improve sensorimotor fusion in free space - Eliminate suppression - Increase vergence ranges and facility - COnsider prism if it is needed to achieve goal
Clinical implications: Pharmacological + Optical penalization for amblyopia?
- Improvement in VA was not substantially better with the addition of a plano lens - Based on this evidence, no cause to change initial amblyopia treatment to atropine + plano lens
Inverse cosmetic prism?
- Improves the cosmesis of strabismus - Eye behind the prism is slightly displaced toward the apex (1mm per 8 pd) Makes the eye look like its in another place (pt is NOT USING THAT EYE)
Monocular eye closure and IXT?
- In Bright sunlight - Over 50% of pts with IXT - Closure of non-preferred eye - Reason unclear
Patching in patients with severe amblyopia clinical implications?
- In patients with severe amblyopia, when prescribed with near activities, 6 hours of patching produced similar improvement in VA to full time patching - Patch patients with severe amblyopia for 6 hours/day
Triggering mechanism for DE XT?
- Inattention - Fatigue - Illness
With the treatment of anisometropic amblyopia in children with refractive correction study, what specific factors did they look at?
- Incidence of resolution of amblyopia - Time course of VA improvement - Factors associated with amblyopia resolution with spectacles
Inverse training prism?
- Increase the fusional vergence demand to train increasing fusional vergence ability - Passive tx
What counts as environmental enrichment and perceptual learning in adult rats?
- Increasing social interactions - Increasing sensory motor activities - Increasing exploratory behaviors
Classifications of XT by time of onset?
- Infantile - Acquired
Why is observation important?
- Initially determine frequency, laterality, and direction before testing begins - Determine cosmesis
Initially, targets are seen as what with sensory stimulation? Then what happens?
- Initially seen as separated by the angle of anomaly - Binocular triplopia - Targets superimposed
Theories of AC development?
- Innate Theory - Sensory Theory - Motor Theory
Treatment of esotropia over 15 pd and angle of anomaly over 15 pd
- Intensive active tx over a long period of time (4-6) months - Angle too large to obtain alignment through divergence - Sensory stimulation - Centration therapy
Results of the levodopa for residual amblyopia study?
1.4 letter improvement in levodopa group compared to the placebo. Not statistically significant
With the reduced contrast sensitivity, how does a young infants view of the world look?
A diffuse image - like looking through wax paper
Hemiretinal suppression theory?
AKA Jampolsky theory
Ocular dominance columns are separated into?
7 discrete columns
Each square on Hess Lancaster is?
8 PD
What is the true critical period?
A distinct onset of robust plasticity in response to visual experience when the initially formed circuit can be modified by experience
With strabismic amblyopia, it is more commonly associated with which type of tropia?
Esotropia
Which layers of the LGN are magnocellular?
1 and 2
Human critical period studies show a peak at age ______ with a plateau after age _______
1-2 8
Contralateral retina projects to which layers of the LGN?
1, 4, 6
The ____________ circuitry seems to be the key plasticity in the visual system
Intracortical inhibitory
Actions of the IR?
1. Depression 2. Excyclotorsion 3. Adduction
Actions of the SR?
1. Elevation 2. Incyclotorsion 3. Adduction
Five pharmacological and environmental therapeutics studied for amblyopia in adulthood?
1. Environmental enrichments 2. Dark exposure 3. Caloric restrictions and inhibition of the GABAergic pathway 4. Valproic Acid 5. Fluoxetine
Actions of the IO?
1. Excyclotorsion 2. Elevation 3. Abduction
Actions of the SO?
1. Incyclotorsion 2. Depression 3. Abduction
What three discovers in the 1960s allowed for more understanding on the complexity of visual development in visually deprived eyes?
1. Invention of microelectrode - let you investigate a single cell in the visual system 2. Anatomic model of the retinal axons as they travel to the visual cortex 3. Development of techniques to visualize how cells in the cortex have similar properties and are grouped together
Helveston and von Noordern two types of microtropia?
1. Microtropia (+) movement on CT 2. Microtropia with identity (-) movement on CT, <A = <EF = <D
Which of the following statements best describes the contrast sensitivity function in anisometropic amblyopes? (CHOOSE 2) 1. Overall optical defocus at all loci of the retina 2. Localized deficit at the location of their suppression scotoma 3. Greater loss of contrast sensitivity at lower spatial frequencies 4. Greater loss of contrast sensitivity at higher spatial frequencies
1. Overall optical defocus at all loci of the retina 4. Greater loss of contrast sensitivity at higher spatial frequencies
When testing temporal and spatial crowding, what three tasks did strabismic patients do worse on?
1. Rapid serial visual presentation 2. Tumbling E VA 3. Gabor alignment with lateral flankers
Large sized primary vertical deviation?
16 pd and over
The retina projects to which four nuclei?
1. The lateral geniculate nucleus 2. The superior colliculus nucleus 3. The pretectum nucleus 4. The suprachiasmatic nucleus
Questions Park's 3 step answers?
1. Which eye is hyper? 2. Is the hyper greater in R or L gaze? 3. Is the hyper greater in R or L tilt? - Superior muscles intort inferior muscles extort
How much strabismus may be cosmetically noticeable?
10-20 pd
If the strabismus is ANY less than ___________, then it is intermittent and not amblyogenic
100% fo the time
What is partial occlusion?
Blurred form perception (atropine, filter to create optical blur)
PEDIG now recommends ____________ with 1 hour near work for moderate amblyopia and ___________ with 1 hour near work for severe amblyopia
2 hours 6 hours
Clinical applications for ATS 2A?
2 hours of daily patching with 1 hour of near work produces an improvement in VA similar in magnitude to 6 hours of daily patching
For moderate amblyopes, what do we Rx?
2 hours of patching with 1 hour of near work, and monitor improvement at 6 week intervals
Improvement in VA from baseline and mean VA at 4 months for 2 hours vs 6 hours of patching in Moderate Amblyopia?
2 hours: 2.4 line improvement and 20/32 6 hours: 2.4 line improvement and 20/32-1
Ipsilateral retina projects to which layers of the LGN?
2, 3, 5
Average onset for accommodative ET?
2-3 years POSSIBLE 4 months to 7 years Intermittent onset - parents sometimes don't notice until almost constant
How much of the population has amblyopia?
2-4%
Form degradation/image deprivation amblyopia?
Blurred retinal image from significant opacity before the age of 6
1 mm on Hirschberg is?
22 pd
Rectus muscle forms a _____ angle between the visual axis and the line of insertion
23 degree
Expected VA decrease from EF alone with 2 PD EF?
20/(20x(2+1)) = 20/60 VA
What counts as severe amblyopia?
20/100 to 20/400
What counts as moderate amblyopia?
20/40 to 20/80
Predicting VA decrease from EF?
20/[20x(pd+1)]
Moderate tropia magnitude?
21-40 pd
In order for visual deprivation amblyopia to occur, what must happen?
Any of the causes MUST HAPPEN BEFORE THE AGE OF 6
At medium spatial frequencies, what contrasts can you see?
At medium spatial frequencies, quite low contrasts can be seen
About __% of strabismus have an A or V pattern
30
If angle kappa is OD 0 and OS 0 But Hirschberg is OD 0 and OS +1.5?
33 pd XT
With Haidinger's Brushes, how do you find the magnitude of EF?
4 mm @ 40 cm = 1 PD
About how long does tropicamide last?
4-6 hours
Study design for The Pattern of Visual Deficits in Amblyopia study?
427 adults with amblyopia or with risk factors for amblyopia compared to 68 normal observers
Timney 1990 research in kittens: In as little as _________ days of MD, in this sensitive period, binocular depth perception is affected in kittens
5 days
Blakemore and Van Sluyters (1974) study: From ____________, the kitten is still within its critical period and is highly plastic
5 to 6 weeks
GABAa antagonist (bicuculline) restored binocular responses in over ____ of neurons in the visual cortex of amblyopic cats (less when replicated)
50%
Oblique muscle forms a _____ angle between the visual axis and the line of insertion
51 degree
Study group of IXT 3?
58 children 3 to under 7 year of age
Size of suppression with worth at 40 cm?
6 degrees
Subjective compliance for 6 hours of patching vs full time?
6 hours reported better compliance
The IOT has found that the critical period for binocularity initiates between ___________ in humans
6 months and 1 year of age
Medium sized primary vertical deviation?
6 to 15 pd
Small tropia magnitude?
6-20 pd
Blakemore and Van Sluyters (1974) study: After _____ days of reverse suturing, there is a complete reversal
9 days
Angles in strabismus?
<D is the objective angle of deviation <S is the subjective angle of deviation <A is the angle of anomaly
Characteristics of the angle of deviation?
<D, objective, found by cover - Direction, frequency, magnitude, laterality, AC/A ratio, cosmesis, and comitancy
ACT = ortho Visuoscopy = 3 nasal EF What is the true angle of deviation?
<Dt = 0 + 3pd = 3pd Microtropia with identity
ACT = 15 pd Visuoscopy is 5 pd of nasal EF What is the true angle of deviation?
<Dt = 15 pd + 5 pd = 20 pd
How do you find the true angle of deviation with EF?
<Dt = true angle of deviation <Dm = measured angle of deviation <Dt = <Dm + EF Nasal EF = + Eso = + Temporal EF = - Exo = -
You are significantly cutting a hyperopic Rx, what should you consider?
A near addition
Which types of patients are more symptomatic A or V pattern?
A pattern exotropia - most when looking down V pattern esotropia - most when looking down
What is the critical period?
A time where the visual system displays plasticity
What is form degradation amblyopia?
Blurred retinal image from significant opacity before the age of 6
Why do we need to know different animals' critical periods?
Essential for understanding amblyopia studies in the subject animal
Bagolini, patient reports crossed diplopia, neutralize, and movement on UCT?
AC
Bagolini, patient reports uncrossed diplopia, neutralize, and movement on UCT?
AC
Worth 4 dot: diplopia, neutralize, UCT movement?
AC
Answer to example 1?
AC and EF
Calculate AC/A PD of 56 mm Near testing at 40 cm ACT @ distance CLXT 20 ACT @ near CLXT 20
AC/A = 5.6 + 0.4(-20- -20) = 5.6/1
AC/A ratio calculation?
ACA = PD (cm) + fixation distance (m) x (angle deviation near - angle deviation far) Eso/BO + Exo/BI -
CN VI innervates?
Abducens nerve LR
Actions of the LR?
Abduction
Most common angle kappa?
About 0.5 mm nasal because fovea is not on pupillary axis, but on visual axis
Size of suppression with worth at 6 m?
About 1 degree
Most examiners can reliably detect deviations of?
About 2 pd
What is the closure of the critical period?
After the end of the critical period, the same visual experience no longer elicits the same degree of plasticity
Etiology of Duane's?
Agenesis of the 6th nerve and nucleus inf division of CN III splits to innervate both the MR and LR - fire simultaneously in adduction - retraction
A and V Pattern strabismus is aka?
Alphabet pattern strabismus
PAC explanation?
All post surgery
Which types of AC have diplopia?
All types besides HAC UNLESS suppression is present
What is alternating occlusion?
Alternate between amblyopic eye and the fellow eye
Which laterality is more favorable for prognosis?
Alternating > unilateral
Other associated conditions that complicate strabismus treatment?
Amblyopia, AC, status of sensorimotor fusion, and visual efficiency
Instruments with mirrors?
Amblyoscope and wheatstone stereoscope
What is the primary angle of deviation?
Amount of deviation when the normal eye is fixating in primary gaze
What is the secondary angle of deviation?
Amount of deviation when the paretic eye is fixating in primary gaze
The number of degrees that the Maddox Rod must be rotated for the lines to be parallel = ?
Amount of torsion
When diagnosing amblyopia, you must have?
An amblyogenic condition
What is a non-comitant deviation?
Angle D changes in different fields of gaze or and/or with either eye fixating
Perfect cross on HBAIT, EF of 3 nasal pd?
Angle of anomaly is 3 pd
What are brief deprivational studies?
Animals are deprived of normal visual experience for a brief period of time to see how much time is needed to observe a neurophysiological change
Amblyopia is more common in anisohyperopia or anisomyopia?
Anisohyperopia
Refractive amblyopia?
Anisometropic (unilateral) or isometropic (bilateral) Meridional (high astigmatism)
What does it mean when <S does not equal <D?
Anomalous correspondence
Cover test: 20 CLET Pt reports uncrossed diplopia Aligned at 10 BO Angle of anomaly? Correspondence type?
Anomaly = + 10 pd Correspondence is UHAC
Cover test: 15 CRET Pt reports crossed diplopia Aligned at 5 BI Angle of anomaly? Correspondence?
Anomaly is 15-(-5) = 20 PAC I
Cover test with older children?
Appropriate letter target
What does contrast sensitivity function assess?
Assess visual resolution over the entire spatial frequency and contrast range
Results - stereoacuity?
Associated with improvement in binocular VA
At low spatial frequencies, what contrasts can you see?
At low spatial frequencies, a large contrast is need for visibility
Brown's vs IO paresis and forced duction?
B (+) IO (-)
What is Krimsky good for?
Estimating magnitude of strabismus in young patients and patients with decreased vision in one eye
Treatment of suppression should begin where? and move to where?
Begin where the patient is not suppressing and move to where they are suppressing. Make sure patient has the potential for normal sensory fusion!
DDx of DVD?
Bilateral overacting inferior obliques or an actual vertical deviation
Primary outcome for the ATS-7?
Binocular VA at 1 year
What is interferometry for?
Evaluating VA potential
Binocular summation and amblyopia?
Binocular mechanisms exist in the amblyopic eye, but the signal is weaker, noiser, and strongly suppressed by the sound eye
The effectiveness of daily periods of _____________ was critical for amblyopia treatment
Binocularity
Timney 1990 research in kittens: Monocularly deprived at 90 days old?
Binocularity unaffected
Brown's vs IO paresis and OA of antagonist SO?
B: Absent IO: Present
Brown's vs IO paresis head posture?
B: Chin elevation IO: Head tilt to the affected side
Brown's vs IO paresis and duction vs version?
B: Duction = version IO: Duction > version
Brown's vs IO paresis and motility?
B: Limited elevation in adduction IO: Limited elevation in adduction
Brown's vs IO paresis and vertical deviation in primary gaze?
B: Minimal or none IO: Hypotropia
If on red lens test, they see crossed diplopia, what prism do you add?
BI
Prism for management of IXT?
BI relieving prism: good sensory fusion
Cover test: 20 CLET Pt reports uncrossed diplopia What type of prism do you add?
BO
If on red lens test, they see uncrossed diplopia, what prism do you add?
BO
The NMDA receptor is made of 2 subunits, the NR2b, which is more common at _______________ an the NR2a which binds during ___________
Birth Adulthood
With age, sensitivity increases and develops a more _________ shape
Band pass shape
Caloroso's Residual Vergence Demand for esos?
Based on dissociated measure
Caloroso's Residual Vergence Demand for exos?
Based on dissociated measure
Caloroso's Residual Vergence Demand for hypers?
Based on dissociated measure
Uncorrected myopia and fusion?
Because of the decreased VA at distance, there may be decreased visual acuity at distance
The inciting amblyogenic factor must occur when?
Before the age of 6
What do you do if exo increases with over correcting prism treatment?
Begin decreasing the prism
Normal eyes and stereoacuity?
Best at highest spatial frequencies
What is amblyopia?
Best corrected VA less than 20/20 in the absence of any structural or pathological anomaly, with one of the following occurring before the age of six: - Significant unilateral or bilateral refractive error - Constant, unilateral strabismus - Form vision deprivation
If you are a V pattern exo, how might you tip your head?
Best in downgaze, tilt up
If you are an A pattern eso, how might you tip your head?
Best in downgaze, tilt up
If you an A pattern exo, how might you tip your head?
Best in upgaze, tilt down
If you are a V pattern eso, how might you tip your head?
Best in upgaze, tilt down
Atropine usage for moderate vs severe amblyopes?
Both are only 2x/week!
What happens with the ZRMV and the PVD at eccentric fixation?
Both the ZRMV and PVD are associated with the EF location = Eccentric Localization
VT improves what?
Both the sensory and motor skills to maximize the patient's sensory and motor potential
What does the major amblyoscope (synoptophore) measure?
Both the subjective and objective angle
What is BDNF?
Brain derived neurotrophic factor
What should you check if there is no improvement in amblyopia with treatment?
Check compliance!! If pt is not compliant, educated pt and parents on importance and follow-up in another 6 weeks
Which muscle is affected? - 4 pd L hyper - Greater in R gaze - Greater in L tilt
L SO - all three circles here
Which of the CN paresis is the least indicative of a serious disease?
CN IV paresis
Ddx of Duane's?
CN VI palsy - more neurological causes
CSF deficit in anisometropic amblyopes compared to strabismic amblyopes?
CSF deficit in anisometropic amblyopes is more widespread than in strabismic amblyopes
If the maddox rod is over the L eye rotated: - Clockwise = ? - Counterclockwise = ?
CW - Extorsion CCW - Intorsion
If the maddox rod is over the R eye rotated: - Clockwise = ? - Counterclockwise = ?
CW - Intorsion CCW - Extorsion
When the NMDA channel is opened, ______ is allowed to flow into the cell to activate the second messenger system
Ca 2+
Clincal pearl with IXT?
Check Randot stereo on all XTs. If (+) RDS, patient does not have a constant XT!!
____________________ have a much more severe effect than anisometropia. Substantial effect between 6 and 18 months of age
Cataracts and stimulus deprivation
Why might there be the decreased vernier hyperacuity in the strabismic amblyopia?
Central retina functions like peripheral retinal with a large receptive field. There is undersampling that occurs so the eye makes false judgements. Distortion of the image
Panum's area increases in size from?
Central retina to peripheral retina
Fixation testing looking to compare?
Central vs eccentric fixation
Neurological etiologies of an acute-onset comitant ET?
Cerebellar astrocytoma, cerebellar medulloblastoma, pontine glioma, Pseudotumor, posterior pontine pilocytic astrocytoma, and nasopharyngeal angiofibroma
When you correct hyperopia, what is more likely to change in comparison to myopia?
Change in alignment because it is so dependent on AC/A (no longer accommodating)
Treatment plan for suppression is based on?
Characteristics of the patient's suppression
The suprachiasmatic nucleus is responsible for?
Circadian Rhythms
Jampolsky theory?
Classical theory on what a suppression zone looks like - Elliptical D-Shaped suppression zone - Fovea to just beyond ZMP - Horizontal > vertical
Adult plasticity fMRI studies show that the critical period is never fully ____________
Closed
After you correct refractive error, when do you follow up?
Every 6 weeks until no improvement (plateau)
How do you calculate the magnitude of the Brock-Givner?
Compare fixation point to the AI: 1 cm @ 1 m = 1 PD
PEDIG ATS 2B study population?
Compare patching for severe amblyopia (VA 20/100 to 20/400) in children younger than 7
What is a paralysis or palsy?
Complete loss or impairment of motor function
What is total occlusion?
Complete occlusion, no form perception
What is normal correspondence?
Condition in which stimulation of the two foveas give rise to a common cortical visual direction
Visual acuity is limited by?
Cone spacing
Common causes of noncomitant deviations in children?
Congenital, trauma, and acute viral
Cause of CN III paresis in kids?
Congenital, trauma, or tumor
When do you do sensory stimulation for AC?
Constant ETs over 15-20 PD
Score 5?
Constant XT before dissociation
Strabismic amblyopia?
Constant unilateral strabismus
Which type of strabismus will lead to amblyopia?
Constant unilateral strabismus
Suppression frequencies?
Constant, intermittent, flashing, and may be present under some conditions and absent under others
What is Herrington's Law?
Contraction of a muscle is accompanied by a simultaneous and proportional relaxation of its antagonist
What is Hering's law of equal innervation?
Contralateral synergists are equally innervated - Move eyes left gaze, LLR and RMR are equally innervated
What is contrast sensitivity like at 2 1/2 months?
Contrast sensitivity is low at all spatial frequencies
What does Levodopa do?
Converts to dopamine via the enzyme DOPA decarboxylase in the peripheral and central nervous system
Adult onset XT?
Decompensated exophoria or pathology
T/F: Magnitude matters for strabismic amblyopia
False! It does not matter
T/F: All patients with amblyopia have eccentric fixation
False: Not all
T/F: Suppression and AC cannot co-exist
False: Suppression and AC can co-exist
T/F: The retina has plasticity
False: The retina is hard-wired at birth
Why might some TBI patients have unstable sensory fusion?
Damage to the cortical area responsible for fusion - sensory fusion disruption syndrome
What is first degree sensory fusion?
Dissimilar contours
What happens if someone has poor sensory processing?
Doesn't stimulate controlling fusional vergence
Levodopa/carbidopa increase _________ levels in the CNS
Dopamine
Who is centration therapy for?
Esotropes may be able to bifixate a target in free space at a very near distance or through high plus lenses (5-15 cm) - May be useful for young children
Temporal displacement on Hirschberg?
Esotropia
ACT and eccentric fixation?
EF contaminates the angle D measurement (objective angle of deviation)
Answer to example 2?
EF no AC yes
Answer to example 3?
EF yes AC no
Fluoxetine can reinstate?
Early-life critical period-like neuronal plasticity
Normal zone of the amblyopia map?
Eastern zone with high acuity and good contrast sensitivity
Orthopic/chiastopic instruments?
Eccentric circles and aperture rule
Environmental enrichment, including increased social interaction, sensory motor activities and visual perceptual learning, was shown to be highly _______ in enhancing plasticity in V1 in rats
Effective
Duane's unilateral or bilateral?
Either
What does suppression do?
Eliminates diplopia and confusion
Ocular dominance column 4?
Equal distribution of cells from both the ipsilateral and contralateral eye
If distance angle = near angle, what is the AC/A?
Equal to the IPD
What is isoametropic amblyopia?
Equally high refractive error
PAC I XT vs ET?
Eso will subjectively report as an exo and the reverse
Directions of deviation?
Eso, exo, vertical, cyclotorsional, and combination
Nasal displacement on Hirschberg?
Exotropia
CN III paresis if complete?
Exotropia, hypotropia, intorsion, ptosis, and fixed/dilated pupil
When do we consider overminusing your patient?
Exotropia: divergence excess, high AC/A or CA/C, and young pts
Motor fusion and targets at different demands?
Expands the motor skills
The superior colliculus is responsible for the control of ______________.
Eye movements
What is flashing intermittent suppression?
Fast on-off awareness of suppressed information
What are the characteristics of suppression?
Frequency, size, intensity, laterality, and latency: - Under which conditions is the suppression present? - Is the suppression constant or intermittent under the same testing conditions? - If intermittent, what is the frequency? - When suppression is absent, does the patient have normal sensorimotor fusion? - Which eye suppressess? - Which part of the retina - What alteration of viewing reduces or eliminates suppression?
T/F: 4 BO is used to diagnose a microtropia
FALSE - Used to diagnose a small suppression scotoma
T/F: HBAIT is a cortical test and it relies on diplopia
FALSE: It is a cortical test, but it does not rely on diplopia
T/F: No facial asymmetry with CN IV paresis
FALSE: May have facial asymmetry
T/F: Some patients during this study developed constant diplopia
FALSE: No patients developed diplopia
T/F: There is a convergence of information from the two eyes in the LGN
FALSE: The information between eyes is still kept discreet. No convergence
T/F: You can predict an amblyopic patient's VA from EF alone
FALSE: You can't
Fusion grades?
First, second, and third degree
With Hess Lancaster, the examiner projected laser is for the ______ eye while the patient projected laser is for the _______ eye
Fixating Testing
Goals of treatment for IXT?
Flom's functional cure
Sensory ET happens when?
Following a decrease in vision in one eye: - Optic nerve hypoplasia - Cataract - Uncorrected anisometropia
The depth of suppression usually correlated with?
Frequency of strabismus
How to differentiate between innervational or mechanical cause of UA?
Forced duction testing
Which type of amblyopia will cause the most drastic issues?
Form deprivation
What do we use to monitor motor stimulation?
Foveal tags
Suppression characteristics?
Frequency, size, intensity, laterality, and latency
Prognosis of accommodative ET?
Good if intermittent or of short duration
Cover test 20 CRET Bagolini aligned Movement on UCT after What type of correspondence?
HAC
Deviation caused by registered eye movements?
HAC
Patient is subjectively ortho but 20 pd ET on cover. What is this?
HAC
Pt reports one light in middle of X on bagolini and unilateral cover test has movement?
HAC
What does out-of-instrument testing tell us about our constant strabs?
How patient functions under normal seeing conditions
Inferior displacement of Hirschberg?
Hyper
Superior displacement of Hirschberg?
Hypo
Patching patients with moderate amblyopia clinical application?
In patients with moderate amblyopia, when prescribed with near activities, 2 hours of patching produced similar improvement in VA to 6 hours of patching Patch patients with moderate amblyopia for 2 hours/day
Signals from the LGN enter V1 at layer ____ which then projects to layer ______ and ____, which sends signals to other areas of the cerebral cortex
IV II III
Why do you need to evaluate comitancy with a longstanding strabismus?
Identifying characteristics of deviation may help with treatment and prognosis
Cause of OAIO?
Idiopathic - Commonly associated with infantile ET
When does maddox rod/red lens test not work?
If AC or deep suppression
When should you NOT use Hess lancaster?
If AC or deep suppression
When to Rx prism if they have normal sensory fusion?
If improves sensory fusion
What if pt reports a perfect cross on HBAIT?
If no EF = NC If EF = AC
IXT2 looked at what and what was the inclusion criteria?
If patching works - 3 to 11 yo pts - Previously untx IXT - Intermittent or const XT at distance - Randot stereo - 15 pd or greater at distance or near - 10 pd or greater at distance
What do you need to identify before evaluating correspondence?
If the patient has EF
HBAIT Patient has a 40 CRET with normal fixation What do you expect to see on HBAIT if patient has unharmonious anomalous correspondence?
If we know EF is zero
HBAIT Pt 40 CRET with normal fixation What do you expect to see on HBAIT if the patient has harmonious anomalous correspondence?
If we know EF is zero
How does EF contribute to decreased VA?
If you increase retinal eccentricity, you decrease visual acuity
How do we use fast pointing for eccentric fixation treatment?
If you take a peg and in one swift movement try to get it into a moving peg board - patient will be redirected from eccentric fixation to fovea.
What is binocular summation?
Improvement in one eye's detection performance produced by subthreshold pattern presented to the fellow eye
Conclusion of the levodopa/carbidopa study?
Improves VA in patients with amblyopia and maintains improved VA, esp in patients under 8 years old
What happens with the zero retinomotor value (ZRMV) and the principal visual direction (PVD) at central fixation?
In central fixation, the ZRMV and the PVD are associated with the fovea
Helveston and von Noordern definition of microtropia?
In each patient, a microtropia not detectable with cover test was demonstrated by showing that these patients used an eccentric area in the deviating eye for both monocular and binocular fixation, thus masking the tropia
ETs (smaller angle) and motor stimulation?
In instrument
Types of sensorimotor fusion testing?
In-instrument evaluation or out-of-instrument evaluation
What do you do after occlusion therapy plateaus and they still have residual amblyopia?
Increase treatment and follow-up every 6 weeks until no improvement
When contrast sensitivity develops, what allows for the increased overall sensitivity?
Increased cone length and funneling capacity
Increased latency?
Increased suppression
How do we visualize the visual cortex?
Inject radioactive amino acids into the vitreous which gets transported along the retinal axons
Paretic noncomitant deviation?
Innervational
Where do you instruct the patient to look with visuoscopy?
Instruct the patient to look at the center of the target
Cover test target for young children?
Interesting target with details
Which frequency is more favorable for prognosis?
Intermittent more favorable than constant
What does a OS temporal EF look like on visuoscopy?
Its 3 PD
Reducing the GABAergic pathway = ?
Keeps the critical period plastic for longer - keeps the gate open
Problem with autorefraction?
Kids very often accommodate in the AR. Wet AR works well because no accommodation
Recession for XT?
Lateral rectus recession
Resection for ET?
Lateral rectus resection
What would a LLR underaction look like on maddox rod if it is placed over the right eye?
Left eye sees the white
Treating partially accommodative ET?
Lenses and additional treatment: Prism, Sx, and VT - Follow-up important because may have developed sensory anomalies
What can be included in the optimum refractive prescription?
Lenses and prism
Treating accommodative ET?
Lenses: - Consider full cyclo - Consider add at near if high AC/A Close follow-up necessary: monitor cover test and RDS stereo
If you have greater exo at near, the AC/A will be _________ than IPD
Less
The more peripheral the EF, the _______ steady it is
Less
Crossed diplopia on bagolini?
Light for the right eye is seen on the left side Light for the left eye is seen on the right side
Uncrossed diplopia on bagolini?
Light for the right eye is seen on the right side Light for the left eye is seen on the left side
Hubel and Wiesel sutured one eye closed in a newborn cat which allows for ____________ but no ______________
Light projection Patterned image on the retina
What causes the higher CSF deficit in anisometropic amblyopes?
Linked to the amount of overall optical defocus
Timney 1990 research in kittens: Monocularly deprived before eyes opened, discontinued by 30 days old?
Little effect on binocularity
Out of instrument motor fusion testing?
Loose prisms and prism bar
What is it called when you need a lot of contrast to see low spatial frequencies?
Low frequency fall off
Where do we set bifocals for a kid 8-9 or over?
Lower lid margin or PAL
Where do we set bifocals for a kid 6-8 yo?
Lower pupil margin
Astigmatism and accommodative demand?
Makes accurate accommodation difficult
Why may a patient turn their head away from the paretic muscle?
Makes the images really far apart and then can suppress one.
NFV and IXT
May also have poor NFV ranges
Problem with recent onset?
May be a life-threatening condition and may need immediate referral
PFV and IXT?
May be low - compare blur/break to size of deviation
Overview of CXT treatment?
May have to work in-instrument
Bifocal and overminusing?
May need an add for near work
Tx for partially accommodative ET?
May need surgery or prism depending on the size of the angle and the patient's goals. Need to evaluate the potential for normal sensory fusion
Occlusion for IXT?
May not be prescribed or on a part-time basis
What does the Hering Bielschowsky After Image Test (HBAIT) measure?
Measures the angle of anomaly directly using foveal tags (angle of anomaly measured) - Take EF into account to determine the TOTAL angle of anomaly (angle of anomaly total) - We do not measure subjective angle
Head turn suspicious of which muscles?
Medial or lateral rectus
Recession for ET?
Medial rectus recession
Resection for XT?
Medial rectus resection
Lateral disparity testing?
Monocular contour/lateral disparity cues
_________________ are our basis for understanding how amblyopia affects the visual cortex
Monocular deprivation studies
If the binocular cortical cell fails to develop binocular responsiveness and is driven primarily by the non-deprived eye alone, it becomes a?
Monocular driven cell
EF will impact any test that uses?
Monocular fixation
Principal visual direction?
Monocularly - we compare all other directions to it - Oculocentric - All other directions are secondary visual directions
Why is strabismic amblyopia most commonly associated with esotropia?
More likely to be constant than exotropia. Most XTs are IXTs. Hard to compensate for esotropia
Hierachy of tests based on how dissociating they are?
More tests that patient has AC and if AC under more dissociating conditions = more embedded = more difficult to treat Most to least dissociating: Hering-Bielschowsky AI test Red lens test Amblyoscope Bagolini (clear lenses in free space)
When do we see eccentric fixation most often?
Most often in strabismic amblyopia but not all strabismic amblyopes
Flom's swing is ________ stimulation
Motor
After sensory fusion has been established, evaluate?
Motor fusion! In-phoropter and out-of-instrument training
If angle kappa is OD +0.5 and OS 0 But Hirschberg is OD +2.0 and OS 0?
Moves +1.5 33 pd XT
Neurologic/systemic disease with Paretic vs Non-Paretic strab?
P: May be present NP: Usually absent
Taxi drivers in London and plasticity?
New taxi drivers in London show measurable neuroplasticity in their hippocampus and temporal cortex after learning to navigate London's complex roads
Adult neuroplasticity and the closure of the critical period?
New technology (fMRI and PET) have given scientific evidence that adult plasticity exists, and the closure of the critical period is no longer thought of as inevitable in neuro-development
Score 1?
No XT unless dissociated: recovery in 1-5 seconds
Score 2?
No XT unless dissociated: recovery in over 5 seconds
What is constant suppression?
No awareness of suppressed info
Brief monocular deprivation in adult rats?
No ocular dominance shift
Will IXT cause amblyopia?
No only constant unilateral!
Prescribing for Exotropia and hyperopia?
No plus or cut plus, unless patient has a huge amount
Study: A kitten who was given normal visual experiences for 4 months, then the kitten is monocularly deprived for an additional three months. What happens to ocular dominance columns?
No shift because the critical period has already closed
If angle kappa is OD +0.5 and OS 0 But Hirschberg is OD +0.5 and OS 0?
No strabismus!
Was there a difference in the study of patients that had really poor VAs vs those who had less poor VAs?
No. They both improved by about 3 lines of acuity
What is ocular torticollis?
Noncomitant deviation, often cyclovertical
Comitancy with Paretic vs Non-Paretic strab?
P: Noncomitant NP: Comitant
Anisometropes and stereoacuity?
Normal at low spatial frequencies, subnormal at intermediate spatial frequencies, and unmeasurable at higher frequencies
Anisometropic amblyopes and binocular summation?
Normal binocular summation at low spatial frequencies but none at high spatial frequencies
You should STOP anti-suppression therapy if the prognosis for?
Normal binocular vision is poor
What does it mean when <S = <D?
Normal correspondence
Pt reports one light in middle of X on bagolini and unilateral cover test has no movement?
Normal correspondence Angle of anomaly is zero
VF results with amblyopia?
Normal or no localizing defects
Suppression creates an obstacle to?
Normal sensorimotor fusion
What retinomotor value does the fovea have?
Normally, the fovea has a Zero Retinomotor Value (ZRMV)
Strabismic zone of the amblyopia map?
Northern zone that shows a moderate loss of acuity combined with a better contrast sensitivity
Results: Pharmacological + Optical penalization for amblyopia?
Not clinically significant improvement
Occlusion for CXT?
Not necessary if quick response to motor stimulation. If no response, may need full time occlusion
What does it mean that amblyopia is a syndrome?
Not only decreased acuity: - Ocular motility - Accommodation - Contrast sensitivity - Spatial distortion
Study design of IXT3?
Overminus spectacles (-2.50 over cyclo) or observation
Evaluating anomalous motor fusion with the progressive prism adaptation test?
Once PA stops, apply an additional 10-15 pd over the fixating eye
Amblyopia before 6 months of age?
Only significant deficits lead to amblyopia before 6 months of age
What does it mean that the suppression is shallow?
Only under natural conditions
BDNF availability is linked with the critical period __________ and __________
Onset and closure
Acquired ET?
Onset over 6 months of age
What did ATS 13 look at?
Optical treatment of strabismic and combined strabismic-anisometropic amblyopia
XTs and motor stimulation?
Out of instrument
How much strabismus is cosmetically noticeable?
Over 20 pd
Large tropia magnitude?
Over 40 pd
What is the CSF loss like for our strabismic patients?
Overall loss across ALL spatial frequencies when compared to normal eyes. Pattern still remains
What did IXT3 study?
Overminus as treatment option for IXT
What is it called when EF is opposite the angle of strabismus?
Paradoxical EF
Maculo-Macula Test of Cupper: what does the fixating look at?
Patient fixates target off to the side with a mirror
Motor fusion and targets at zero demand?
Patient has to have the vergence skills equal to the strabismic angle
Timney 1990 research in kittens: Monocularly deprived between 35 and 45 days old
Peak of sensitive period with a rapid decline in susceptibility outside those age limits
What is PEDIG?
Pediatric eye disease Investigator Group - Collaborative network - Research in strabismus, amblyopia, and other pediatric eye disease - Funded by the NEI
HBAIT Pt 40 CRET with normal fixation What do you expect to see on HBAIT if they have normal correspondence?
Perfect cross at 0
How do you do Krimsky?
Place prism over the deviating eye and change power until reflexes are symmetrical
When do we want to put someone with strabismus into VT?
Poor motor control, poor sensory processing
Angle Kappa sensitivity for EF?
Poor sensitivity for EF (too small typically)
What is a myectomy?
Portion of the muscle excised
Long-term potentiation strengthens the __________ connection
Pre and post synaptic
Amblyopia is predominantly unilateral or bilateral?
Predominantly unilateral and less commonly bilateral
Goal of oveerminusing?
Prescribe the minimum amount of minus needed for fusion at distance and near
Primary vertical deviation?
Present when eyes are straight
Primary outcome: Treatment of amblyopia in children 7-17 years?
Primary outcome: percentage of patients classified as a responder - Amblyopic eye acuity was 2 lines better than baseline at 6, 12, 18, or 24 week f/u - Non-responder if patient has not improved 2 lines at 24 weeks
Primary outcomes for PEDIG ATS 2B?
Primary outcomes measured was VA in amblyopic eye after four months
Over-acting inferior obliques is aka?
Primary overaction of the inferior oblique OAIOs
The pretectum nucleus is responsible for the control of ____________.
Pupils
Ocular dominance column 1?
Purely contralateral cells
Ocular dominance column 7?
Purely ipsilateral cells
Score 0?
Purely phoria: under 1 sec recovery after dissociation
Levodopa acts on dopamine receptors where in the eye?
RPE, photoreceptors, amacrine, and horizontal cells
The eye with the ____ filter sees the red laser and the eye with _____ filter sees the green laser
Red Green
___________ GABAergic inhibition facilitates synaptic plasticity
Reduce
Visual changes with amblyopia?
Reduced acuity, contrast, spatial localization, positional localization, and stereo
Studies of Levodopa?
Reduction of GABAergic inhibitory pathway would be able to restore plasticity in the visual system
What is motor fusion?
Relative movements of the two eyes in response to disparate retinal stimuli to obtain and maintain simultaneous simulation of corresponding areas so sensory fusion can occur
Maculo-Macula Test of Cupper: Patient reports?
Relative position of the fixation target and the visuoscope target
What can you do with rebound saccade and ACT?
Repeat several times
What was the result of occlusion of 3.5 hours vs 5 hours per day in kitten studies?
Resulted in normal acuity, contrast sensitivity, and vernier acuity in both eyes
Initial processing of an image takes place where?
Retina
Dopamine increases _______________ playing a role in retinal blood flow hemodynamics
Retinal vessel diameter
RHT on bagolini?
Right is high so it sees the dot low Left is low so it sees the dot high
LHT on bagolini?
Right is low so it sees the light high Left is high so it sees the light low
In a paretic deviation, which is larger? Primary or secondary deviation?
Secondary will be much larger
______________ is the second most common presenting sign for a retinoblastoma
Sensory ET
Motor fusion and the target at the strabismic angle?
Separation of the vergence system from the sensory processing system
Which type of VA do amblyopes do the best at?
Single letter
Deviation caused by partly registered / parly non-registered?
UHAC
What does it mean if UA on duction testing?
Severe mechanical or innervational anomaly
Monocular derivation in a newborn cat for three months resulted in?
Severe vision loss in that eye
Which duration is more favorable for prognosis?
Short duration
LTP produced a long-lasting increase in?
Signal transmission between two neurons
What causes refractive amblyopia?
Significant refractive error
What is second degree sensory fusion?
Similar contours
What is the vernier acuity like for anisometropic amblyopes?
Similar to that of non-amblyopes when scaled
What is a paresis?
Slight or incomplete paralysis
What is intermittent suppression?
Slow on-off awareness of the suppressed info
Haidinger's Brush + AIT is useful for?
Small angle strabismic patients with EF
Which magnitude is more favorable for prognosis?
Smaller is not necessarily easier to treat. It is a factor in VT though.
With Pratt-Johnson scotoma, it is ________ in ETs and _________ in XTs
Smaller, larger
Anisometropic zone of the amblyopia map?
Southern zone that shows a moderate loss of acuity with worse than normal contrast sensitivity
The NMDA receptor activity leads to _____________ of the synapse
Stabilization
Why do we want to establish the conditions under which sensory fusion can be established?
Stable sensory fusion will keep the patient from suppressing.
What is Brown's Syndrome AKA?
Superior oblique tendon sheath syndrome
What must you identify with suppression?
The conditions under which suppression occurs: important for prognosis and treatment plan
The inter-ocular transfer paradigm can be used to measure?
The critical period
What is the CSF deficit like in strabismic amblyopia?
The deficit is localized around their suppression scotoma
The Pattern of Visual Deficits in Amblyopia study conclusions for strabismic amblyopes?
The deficits in optotype acuity and vernier acuity were disproportionately greater than the deficit in grating acuity
Visual deprivation from dark rearing in adults stimulates ________________ to the NMDA receptor
The delivery of NR2b
What is the pre-critical period?
The initial formation of neuronal circuits that is not dependent on visual experience
How do we use Haidinger's brushes for eccentric fixation treatment?
The patient has to move the brush to a fixation point - then clarity increases (through a maze etc)
From Mitchell (1991)'s study on the long-term effectiveness of different regimens of occlusion in MD Kittens: Considerable behavioral and physiological recovery can occur if normal visual input is restored to the deprived eye by?
The non-deprived eye having full time occlusion
What is a hyperacuity?
The normal vision system is capable of discriminating offset smaller than a cone's diameter. This allows for better acuity than predicted by optical or anatomical consideration
On ACT, how can you tell which eye has the paretic muscle?
The one with the larger primary gaze pd
In the Treatment of amblyopia in children 7-17 years study, what happened to those older children that had not been previously treated?
Those showed greater improvement in the treatment group than spectacle only group
Study design: Treatment of amblyopia in children 7-17 years?
Thought was they wouldn't improve at all so they threw everything at it
There is ___________ organization at the LGN
Topographic
Head tilt is seen with what kind of diplopia?
Torsional and vertical diplopia
If a patient has a head turn, which direction do they generally turn?
Toward the paretic muscle
Common causes of noncomitant deviations in adults?
Trauma, vascular, and neoplasm
What did ATS - 7 look at?
Treatment of bilateral refractive amblyopia in children 3 to under 10 years old
Long-standing vertical deviation?
Treatment of the vertical deviation: - Prism - Surgery - VT
15 PD esotropia using Caloroso's?
Trial frame
Three types of Duane's Retraction Syndrome?
Type 1: limitation of abduction Type 2: limitation of adduction Type 3: limitation of both abduction and adduction
A smaller enclosure on Hess Lancaster represents the ___ eye while a larger enclosure represents the _____ eye
UA and OA
Patient subjective angle is 10 ET and cover test is 20 ET. What is this?
UAC
Common AC response in XT with HBAIT?
Uncrossed - different than diplopia!
With monocular fixation, what are you looking at?
Under monocular conditions, what portion does the patient use fixate on object. Fovea or non-fovea point
What is anisometropic amblyopia?
Unequal refractive error
What does an amblyopic visual cortex look like with an amblyopic eye ?
Unequal signal between the two eyes. Thin column = deprived eye
Which causes more vision loss? A unilateral deprivation or a bilateral deprivation? Why?
Unilateral because there is form deprivation IN COMBO with abnormal binocular interaction
Which is easier to treat? Unsteady or steady EF?
Unsteady is easier to treat
Which is more common? Unsteady or steady EF?
Unsteady is more common
About how long does cyclopentolate last?
Up to 24 hours
Sensory fusion central target size?
VIsual angle between 1 and 10 pd - within macula
What about active amblyopia therapy?
VT can decrease the total treatment time
Causes of CN III paresis in adults?
Vascular/ischemic, aneurysm, and undetermined
Ocular motility comitancy testing?
Versions, ductions, and forced ductions
Secondary vertical deviation?
Vertical present in the dissociated position which is not present when eyes are bifoveally fixating a target - common in large angle IXT
With the vertical muscles, how do you isolate the vertical action?
When the plane of the muscle tendon parallels the visual axis
The Pattern of Visual Deficits in Amblyopia study research question?
Whether visual abnormality is completely characterized by the deficit in optotype acuity, or whether it has distinct forms that are determined by the conditions associated with the acuity loss (such as strabismus or anisometropia)
Testing options for out-of-instrument?
Worth Dot Testing Bagolini 4 prism BO test
Anisometropic hyperopic amblyopia?
≥ 1.00 D
Anisometropic astigmatism amblyopia?
≥ 1.50 D
Isoametropic astigmatism amblyopia?
≥ 2.50 D
Anisometropic myopic amblyopia?
≥ 3.00 D
Isoametropic hyperopic amblyopia?
≥ 4.00 D
Isoametropic myopic amblyopia?
≥ 6.00 D