Boards - Ocular Motility and Binocular Vision
How many duction movements are there?
6, because 6 EOMs!
What percent of all BV disorders are secondary to accommodative dysfunction?
70-80%!
How far away should the ophthalmoscope be when performing Bruckner?
80-100 cm
When performing BCC, what axis should the JCC lens have?
90 (red dots vertical)
What are two *congenital* conditions that could cause a *positive forced duction* test (so besides the usual Graves' tumor, entrapment, etc.)
Duane's retraction syndrome and Brown's syndrome
Box: True or false. Intermittent exotropes with divergence excess commonly have a main complaint of diplopia.
FALSE! True of divergence excess in phorias, but in intermittent tropes, they commonly suppress or develop ARC
True or false. Treating the horizontal phoria will often lead to resolution of the vertical.
FALSE, the opposite! Treating the vertical phoria will often lead to resolution of the horizontal
True or false. Optokinetic nystagmus does not require visual input.
FALSE. It DOES require visual input, which is why it has a *longer latency* than the VOR!
Box: How do you differentiate fusional vergence dysfunction from accommodative infacility?
FVD will have abnormal bino accom facility testing but normal mono accom facility, while patients with accom facility will fail both
What are the tests for *ocular alignment?*
Hirschberg/Krimsky Major amblyoscope Bruckner 4 BO test
____________________, or asymmetry between the eye movement velocity and the target velocity during pursuits, may occur secondary to lesions of the CNS or due to medications, such as alcohol or tranquilizers.
Low pursuit gain
True or false. An abnormal MEM may reflect an accommodative OR a binocular disorder.
TRUE
True or false. Percival's criterion doesn't even take into account the phoria of the patient.
TRUE
True or false. The VOR is driven by the EAR, not the eye.
TRUE; does NOT require a visual stimulus; driven by endolymph in semicircular canals
Box: Which type of target (zero, first, second, third) is used for anti-suppression therapy?
*first-degree*, aka superimposition targets (completely dissimilar so more difficult to suppress/will see diplopia)
vergence initiated by *retinal image disparity*
*fusional vergence*, aka *motor fusion*
jerk nystagmus that occurs only at extreme gazes (horizontal or up), may be conjugate or disconjugate, and occurs in the presence of *other ocular motor abnormalities*; may develop secondary to drug use (e.g. alcohol, anti-convulsants, sedatives), or _____________________ disease
*gaze-evoked nystagmus; posterior fossa*
AC/A calculated by changing the *stimulus to accommodation, NOT the distance* (same distance)
*gradient AC/A*
When performing smooth vergences, the reserve recovery should at least be what amount?
*half of the break*
Box: In order for a patient to be comfortable, _________ of the accommodative amplitude should be kept in reserve.
*half*
Damage to the vestibular system, whether central (vestibular nuclei in brainstem/cerebellum) or peripheral (labyrinth or vestibular nerve) can result in an imbalance of output and a resulting _______________________.
*horizontal nystagmus*
a *spatial representation of all points in space that are imaged on corresponding retinal points* in the two eyes, on which any object will be seen as single
*horopter*
both eyes rotate about the y axis such that the upper portion of each eye tilts toward the midline
*incyclovergence*
*Dissociated vertical deviation* and *latent nystagmus* are both conditions often found with what other condition?
*infantile ET*
type of nystagmus that has a slow and fast phase; Which phase represents the abnormality?
*jerk nystagmus*; *slow phase* (fast is the correcting saccade)
rotations about the y axis such that the upper portion of both eyes tilts to the patient's left
*levocycloversion*
*Vergences* are *disconjugate* eye movements that occur with a latency of about _____________ msec, with a velocity of ____________________.
160 msec (similar to other eye movements, except saccades which are slow, 200, and VOR which is fast, 15); 10 deg/sec (SLOW)
When does unharmonious ARC usually occur?
2-3 wks after strabismus surgery as the visual cortex transitions
What is the expected value for stereo?
20 secs of arc and ability to detect gross random dot targets
For BV testing, what target should be used?
20/30 line or 2 lines above the BVA
What rate do you increase prism when performing both smooth and step vergences?
2^/sec
In *caloric testing*, the patient is positioned so that the head is elevated ________ degrees. The head is turned to one side and water is slowly poured in the inner ear. In a patient with an *INTACT* vestibular system, *warm water poured in the right ear will result in a slow conjugate movement to the ___________* with a resulting fast movement back towards the ____________ (caloric nystagmus). What's the mnenomic to remember this?
30; *left*; right *FAST COWS*: cold-opposite, warm-same (for FAST phase! And remember... this is the NORMAL response!)
When performing the Hirschberg test, how far away should you be from the patient's midline? What are you comparing?
50 cm; *corneal reflex (Purkinje image 1!)* to the pupillary axis
Box: If an object moves at a velocity greater than __________ deg/sec, the eyes can no longer maintain a smooth tracking movement. A voluntary saccade will be necessary to place the fovea on the target again, resulting in a continuous pursuit-saccade-pursuit process.
50 deg/sec
The superior rectus inserts on the top of the eye ______________ to the equator and _______ degrees *temporal* to the line of sight. What are its primary, secondary, and tertiary actions?
anterior; *23 degrees*; *elevation => incyclotorsion => adduction*
Box: What are the two types of fixational eye movements associated with neural noise in the brainstem? What eye movements counteract these errors of monocular fixation?
microdrifts and microtremors (both disconjugate and unintentional); *microsaccades*
What are the three types of eye movements associated with fixation (hold eyes in place when head is motionless)?
microsaccades, microtremors, and microdrifts
Eccentric fixation will only develop in an eye with a stable, constant, unilateral __________________________ of longstanding duration during the developmental sensitive period.
microstrabismus
What is the most repeatable method for measuring phorias?
modified Thorington
How do you test for midline shift syndrome? How is it treated?
move target to patient's right and left, and ask when it's in the midline; if not the true midline, document; *yoked prism* with base towards the *neglected side*
The cortical regions of the brain responsible for the OKN response are not fully developed at birth. As a result, the _________________________ OKN is ABSENT in infants <3-4 mo.
nasal to temporal (more important to see something coming at you from outside your field of vision anyway!)
Which fusional vergence ranges are reduced in divergence excess? These patients may also have what kind of exo?
neither! PFV at distance and near usually *NORMAL*; *V-pattern exo*
Box: In *covariance*, when is harmonious ARC used instead of NC, when the normally fixating eye is fixating or when the strabismic eye is fixating?
normally fixating eye
the line passing through the NODAL POINT that's normal to the surface of the cornea, based on the center of curvature
optical axis
When you do a Park's 3-step, you're basically trying to differentiate between what two kinds of CN palsies?
partial 3 or 4
Box: How can you distinguish physiologic nystagmus from pathologic nystagmus if you're not sure?
pathologic is often associated with other oculomotor abnormalities, so evaluate BV, OKN response, VOR, saccades, and pursuits
There are two overall categories of nystagmus, ______________________ and ___________________. Which one is characterized by dissociated (disconjugate) eye movements with excessive drift?
physiologic and pathologic; pathologic
Does the inferior oblique insert anterior or posterior to the equator? At what angle, and medial or temporal to the line of sight?
posterior; *51 degrees*; *medial* (same as superior oblique, but a little smaller angle than 54 because it's "inferior")
People with pursuit dysfunction will have what symptoms?
primarily trouble with *sports*; excessive head movement while tracking objects
the line perpendicular to the cornea at the center of the pupil
pupillary axis
*Hess-Lancaster test*: When the patient puts on the red green glasses, should the red lens be over the fixating or non-fixating eye when measuring the primary deviation, if the doctor's holding a red flashlight?
red over fixating eye (so patient will have a green light and will be moving it wherever their non-fixating eye points... then switch so red is over non-fixating eye to measure secondary deviations)
Box: NPC may also be performed with a penlight while the patient wears __________________ glasses.
red-green glasses (break point when they see 2 colored lights... may be worse dissociated)
Neglect is most often caused by damage to what part of the brain?
right front parietal lobe
When performing Krimsky, do you add to the eye with the displaced reflex (strabismic eye) or the fixating eye? Do you have to take angle lambda into account?
the *fixating eye*; no (just neutralizing until equal with other eye's reflex, so cancels out lambda)
A patient's NPC is receded, so you decide to perform it with a plus lens. If this is a true CI, what will happen?
the NPC will be WORSE because plus stimulates PFV (in contrast to pseudo-CI, where it will make it BETTER)
The superior oblique passes through the trochlea and travels diagonally to insert on the _______________________ region of the eye _____________ to the equator and at an angle of ________ degrees *medial* to the line of sight. What are its primary, secondary, and tertiary actions?
upper temporal; posterior; *54*; *incyclotorsion => depression => abduction*
Saccades are very *rapid, yoked* eye movements that move the fovea to an object. They have a FAST _____________ (reaching 1000 deg/sec!) but a SLOW ________________ (200 msec). They can be either *voluntary OR involuntary*. *Microsaccades*, characterized by smaller amplitude and velocity (10 deg/sec), are used for reading and occur approx. ______ times a min.
velocity (FASTEST eye movements!); latency; 5
small, intermittent, conjugate jerk nystagmus apparent in extreme (>30 degrees from midline) horiz positions of gaze; often worse when tired
*end-point nystagmus*
What is the equation for gradient AC/A?
(P1 - P2) / (S1 - S2)
What is the equation to find *calculated AC/A*?
*(15 - D + N) / 2.5* OR if PD is given, first find conv. stimulus instead of 15, which is: *PD(cm) / WD(m)*
What is a normal angle lambda?
*0.5 mm nasal* (2-3 deg) in each eye
The VOR is stimulated by what?
*endolymph in the semicircular canals* (does NOT require visual stimulus)
Box: The amplitude of accommodation measured with the minus lens test is __________ ________ than the amplitude obtained with the push-up test. Why? How can the effects of this be avoided?
*2.00D less*; due to *minification* of the image as minus lenses are added; Can avoid effects of minification by placing target at 33cm but still using 2.50 for calculation
Box: The amplitude of accommodation found from the *minus lens test* is amount of minus added over the patient's prescription PLUS ____________.
*2.50* (to account for working distance of 40 cm)
Box: A *1mm shift of light reflex corresponds to _____ prism diopters.*
*22*
A *microesotropia* is defined as a constant unilateral eso <10^ that develops before age ________. Do we want to mess with these?
*3 yo*; NO, HIGHLY likely to lead to intractable diplopia!
Although the VOR compensates well for fast head movements, the reflex begins to *fade* with sustained head movements over ___________________ in duration; then the ________________________ takes over and is responsible for continuing eye movements in response to continuous head movements (e.g. spinning around in a chair).
*30 seconds*; *optokinetic system*
Worth dot detects suppression AND flat fusion ability. Testing is indicated if *stereo is worse than _____________.*
*40 secs of arc*
*Secondary ET* is due EITHER to a sensory deprivation or consecutive ET after strabismus surgery. The sensory deprivation must occur AFTER the age of ________.
*5 yo*
If foveal misalignment occurs before the *age of ________*, the visual cortex may respond by developing *ARC*.
*5 yo* (EARLIER than amblyopia!)
*Sensory exotropia* MUST occur AFTER what age? This is due to what?
*5 yo*; acquired vision loss in one eye
*Infantile ET* must occur before what age? Acquired ET (accommodative, acute, mechanical, secondary, microesotropia) ALL occur *AFTER this age*.
*6 mo*
Box: Amblyopia only occurs from dissimilar retinal images during the *critical period* of visual cortex development. What is that critical period?
*7-9 yo* (first 2-3 yrs most sensitive)
Box: What's the difference between *accommodative excess* and *accommodative spasm*? Which one will *plus lenses help*?
*Accommodative excess* - when the patient over-accommodates to ANY stimulus *Accommodative spasm* - result of fatigue due to over-stimulation of accommodative system *Plus lenses* will only reduce the symptoms of *accommodative spasm* (do not work as well for excess... ??)
the area between the tangential point and the point of insertion of the muscle on the globe of the eye; the area where the muscle exerts its action
*Arc of contact*
What's the most common non-comitant deviation after trauma?
*CN 4 palsy*
What are the two most common causes of vertical diplopia?
*CN IV palsy* and *TED*
Box: What is an important differential for *divergence insufficiency*? Both present with what symptoms? How can you tell them apart?
*CN VI palsy*; sudden onset diplopia at distance with large eso; *comitancy* (CN VI is non-comitant)
states that for ANY position of gaze, the eye has a unique orientation in 3 dimensions of space, which is ALWAYS the same for a particular gaze, regardless of where the eye started (i.e. the starting location of the eye and the path taken to a unique position gaze does not influence the orientation of the eye at the final position of gaze)
*Donder's law* ("Donder Wondered..." picture eyes up to the side, thinking...)
a very small misalignment of the visual axes (*minutes of arc*) that is not observed with standard tests for ocular alignment, and still allows the patient to see *singly* since objects still fall within *Panum's fusional area*
*Fixation disparity*
states that synergistic muscles of the two eyes must receive equal innervation for smooth eye movements with single vision; What are the muscle pairs?
*Hering's law of equal innervation* (i.e. yoked muscles); From *different eyes*: LR and MR, *SR and IO*, and SO and IR
What is the most selective subjective test for comitancy?
*Hess-Lancaster test*
states that the eye *must rotate around axes* to achieve a given direction of gaze, which are all located in a *single plane*
*Listing's Law*
Box: The *Spiral of Tillaux* describes the line of insertion of the recti muscles on the globe. Which one has the most anterior insertion site, thus having the strongest effect on the globe when it contracts?
*MR* (SLIM... MR is closest to the limbus, ie most anterior)
Box: Does the *push-up method* under- or over-estimate the amplitude of accommodation? Why?
*OVERESTIMATES because of relative distance mag*
Box: __________________________ refers to abnormalities in fixation, saccades, and pursuits. Patients with this should undergo a complete binocular, accommodative, and visual perception eval.
*Oculomotor dysfunction*
Box: _________________ describes the area immediately around the horopter where objects are still seen as single and in depth, even though they're off the horopter. Any object outside this space is seen as diplopic. Similarly (but NOT the same), ____________________________ is the area around a corresponding *retinal point* where objects are still seen as single and in depth.
*Panum's fusional space*; *Panum's fusional area*
a condition that can occur post-TBI or stroke in which there is a disruption in the ambient visual process responsible for peripheral fusion and spatial organization/orientation, resulting in an unstable visual processing system; patients are often overwhelmed in crowded environments with lots of movement; often frequently have an *increase in myopia*
*Post Trauma Vision Syndrome*
What test assesses the sensory status of the patient (suppression and stereopsis)?
*Randot* Worth 4 dot
What are the types of *physiologic nystagmus*?
*endpoint nystagmus, optokinetic nystagmus, caloric nystagmus,* and *rotational nystagmus*
*Brown's syndrome* involves an abnormality of the _________ muscle AND tendon, OR an abnormality of the ___________________. It may be acquired (inflammation, scarring) or congenital (muscle too short or tendon inelastic). It's usually unilateral and characterized by a small *HYPOtropia* in primary gaze, with *limited elevation during ___________________*.
*SO*; trochlea; *ADduction* (SO too tight, holds it down) HYPO => "Mr. Brown is gettin' Down"
Box: Research suggests that ___________________ is most effective when prescribing prism for *exophorias* while ______________________ is most effective when prescribing prism for *esophorias*.
*Sheard's criterion*; *Percival's criterion*
states that agonist and antagonist EOMs of the *SAME eye* are reciprocally innervated, meaning when the agonist is excited, the antagonist is inhibited by the same amount; What are the muscle pairs?
*Sherrington's law*; From *same eye*: SR and IR, IO and SO, LR and MR "They have to SHARE the fun and take turns"
Box: The ___________________ describes the fading of peripheral images when the eye is fixated on a central object. The small, involuntary movements that occur during fixation help to minimize this effect.
*Troxler effect*
Box: With the *phi phenomenon*, will an eso patient see the image move with or against the paddle? What about an exo patient?
*against*; *with* (image moves in the direction the eye is moving!)
Box: Once a saccadic movement has started, the saccade system *cannot change* the _____________________ in response to a change in object position, resulting in the most common error of __________________.
*amplitude*; undershooting
Box: the angle between the visual axis and optical axis (line passing through nodal point that's normal to the cornea)
*angle alpha* (Note: KMK is wrong, says pupillary axis instead of visual axis)
Box: the angle between the optical axis and fixation axis (line extending from fixation point through the center of rotation of the eye)
*angle gamma*
Box: the angle between the pupillary axis and visual axis (line passing from fovea through nodal point of eye)
*angle kappa* (closely approximates lambda)
What is the only angle of the eye we can measure clinically? (Hirschberg)
*angle lambda*
Box: The amount of prism required to neutralize fixation disparity
*associated phoria*
What is the most common symptom of basic esophoria?
*avoidance of near work*
the axis perpendicular to the muscle plane around which the eye rotates when acted on by an EOM
*axis of rotation*
What must a patient have in order to have any *global stereopsis*?
*bifoveal fixation*
*Accommodative convergence* is initiated by what?
*blur*
The VOR stabilizes images on the fovea during _____________________________ by producing an eye movement of equal magnitude to the head movement in the *opposite* direction. Does it occur rapidly or slowly? Does it have a short or long latency?
*brief head movements*; VERY rapidly (300 deg/sec!) very small latency (15 msec)
Box: Ocular flutter and opsoclonus are typically associated with *____________________ disease*. What are some additional disorders characterized by abnormal saccades?
*cerebellar Dz*; Myasthenia Gravis Parkinson's Alzheimer's ocular motor apraxia progressive supranuclear palsy internuclear ophthalmoplegia (MS!)
For an object to be perceived as single in BV, the image on the retina must be what three things?
*clear, same size,* and fall on *corresponding retinal points*
*What is the most common abnormality of pursuits*?
*cogwheeling*, a series of step-like eye movements used to follow a moving object, rather than smooth pursuits
Under binocular conditions, the foveas of each eye share a *________________________________ direction.* All other corresponding retinal points have a *___________________________ direction*.
*common subjective principle visual direction*; *secondary common subjective visual direction*
List the types of *pathologic nystagmus*
*congenital (infantile) nystagmus, latent nystagmus, spasmus nutans, convergence-retraction syndrome, gaze-evoked nystagmus*, and *see-saw nystagmus*
What is the *most common binocular dysfuntion* in patients with a TBI, found in about 40% of them?
*convergence insufficiency*
points in each eye that have the same visual direction and project to the same area in the visual cortex
*corresponding retinal points*
What tests can determine the magnitude and direction of the ocular deviation at distance and near?
*cover test* Von Graefe Maddox rod modified Thorington card fixation disparity
What can lead to horror fusionis after a TBI?
*cyclovertical heterophoria* (do double Maddox rod testing)
both eyes rotating about the z axis to the *right*
*dextroversion* (left is levoversion)
Is Maddox rod an associated or dissociated test? Does it allow objective or subjective determination of the magnitude and direction of a deviation? Can it differentiate a tropia from a phoria?
*dissociated*; *subjective*; *NO*
Is modified Thorington an associated or dissociated test? Does it allow objective or subjective determination of the magnitude and direction of a deviation? Can it differentiate a tropia from a phoria?
*dissociated; subjective*; *NO*
Which is the *LEAST common* non-strab BV disorder?
*divergence insufficiency*
Box: The ___________________________ test involves one Maddox rod over each eye, and it's used to detect a _______________ misalignment of the eyes.
*double Maddox rod test*; *torsional*
*unintentional, DISconjugate* eye movements that are larger and slower than the other fixation eye movements, with velocities of only 1 arcmin/sec and amplitudes of 6 arc/min; they are likely secondary to neural noise in the brainstem
*microdrifts* (Note: makes sense that both microdrifts and microsaccades are 6 arcmin, because the microsaccades are CORRECTING the drift by moving the eye back where it was! So they SHOULD be the same amplitude)
*intentional, conjugate* eye movements with a moderately *high velocity* (2-10 deg/sec) and amplitude (6 arc min); move the fovea back on an object of interest after the other fixation eye movements have caused the fovea to shift from the target
*microsaccades* (Note: makes sense that both microdrifts and microsaccades are 6 arcmin, because the microsaccades are CORRECTING the drift by moving the eye back where it was! So they SHOULD be the same amplitude)
*unintentional, DISconjugate* eye movements with a high frequency (65-75 Hz) and amplitudes of about 10 arc minutes; these are the *fastest* of the three types of fixation eye movements; because they are disconjugate, they're thought to be the result of neural noise within the brainstem
*microtremors*
a condition caused by a TBI or stroke that leads to a disconnect in the feedback loop between sensory and motor systems, which causes a distortion of space: an expansion of space on the "good side" and a shift away from the neglected side; associated findings include hemiparesis, hemiplegia, neglect, dizziness, balance issues, tilted floor
*midline shift syndrome*
Is angle lambda measured under binocular or monocular conditions?
*monocular*
Box: ___________________ is a vergence eye movement stimulated by retinal disparity that moves the eyes to align each fovea with an object. ______________________ involves combining two images from each fovea into a single percept in the visual cortex.
*motor fusion; sensory fusion*
Box: If patients present with *sudden symptoms* characteristic of a CI, _____________________ and ___________________ must be considered as differentials as they often present with similar symptoms. Remember that patients with a true CI will often have *longstanding* symptoms.
*multiple sclerosis; myasthenia gravis*
the plane that describes the direction of pull of an individual extraocular muscle, passing through the center of rotation of the eye and determined by the origin and insertion sites (perpendicular to the axis of rotation)
*muscle plane* (e.g. for SR, axis of rotation is horizontal, muscle plane is vertical)
Box: Patients who suppress at _____________ and with the room lights _____________ have a *large and deep suppression*.
*near; dim*
Box: The _______________ is the direction of gaze where the nystagmus has the *lowest* amplitude. The _______________________ is the direction of gaze where the nystagmus *changes direction*.
*null point*; *neutral point*
multiple, spontaneous, conjugate horizontal saccades ("spring-like") that decrease in amplitude over time and occur after a series of small saccades or during fixation
*ocular flutter*
Box: *Primary/secondary visual directions* of each eye are in reference to the *EYE* position (___________________) under *MONOCULAR* conditions. *Common subjective visual directions* are in reference to the *HEAD* (____________________) under *BINOCULAR* conditions.
*oculocentric; egocentric*
In ________________________ *testing*, the patient is asked to fixate on a distant target while the head is moved from side to side or up and down. A normal response is to see a conjugate eye movement in the direction opposite to the head rotation.
*oculocephalic* (doll's head maneuver)
advanced form of ocular flutter that appears as an almost constant series of involuntary conjugate saccades in multiple directions that occurs ONLY WHILE AWAKE
*opsoclonus*
maintains a *stable image of a MOVING object on the fovea when the head is STILL*
*optokinetic nystagmus*
conjugate jerk nystagmus for maintaining the image of a moving object on the fovea when the head is STATIONARY
*optokinetic nystagmus* (DIFFERENT from optokinetic reflex, which is due to prolonged head movement!)
Box: _______________________ is characterized by the sensation of *objects* moving up and down in the visual field, while ____________________ is the sensation of the body moving around in the environment, even though it is still.
*oscillopsia; vertigo*
angle of anomaly > objective angle
*paradoxical ARC*
*Pursuits* are controlled primarily by the ______________, though the _________________ may also be involved. Any lesion will cause impaired pursuits towards *the ________________________ side.*
*parietal lobe*; frontal eye fields; *IPSILATERAL* (Note: lesion in parietal lobe, occipitoparietal junction, brainstem, or cerebellum could all cause abnormal pursuits)
*Contour testing* is better for detecting what kind of stereopsis?
*peripheral stereopsis* (>60 secs of arc)
term to describe the time frame when amblyopia can be successfully treated
*plastic period* (up through teen years, even into adulthood)
the line of sight going through the fovea
*primary visual direction* (all other lines of sights are *secondary visual directions*)
Patients with accommodative excess may also have what?
*pseudo-myopia*
In ________________ *testing*, a patient is slowly rotated in a chair for about 20 sec as the examiner watches the eye movements. A normal response involves a slow conjugate eye movement in what direction, followed by a fast response in which direction?
*rotational*; opposite the direction of rotation; toward the body's movement ??? (Note: KMK says slow movement is in direction of rotation, but pretty sure this is wrong... with VOR, eyes move OPPOSITE the rotation)
characterized by elevation and intorsion of one eye with depression and extorsion of the fellow eye in a pendular OR jerk waveform (down and out, up and in); It is associated with what kind of lesions?
*see-saw nystagmus*; *parasellar* (e.g. pituitary tumor! so may see with bitemporal VF defect!)... may also be congenital though "Riding a see-saw with a parasol"
nystagmus that develops within 4-12 months after birth and *resolves* after 2-8 years; often affects multiple family members
*spasmus nutans*
The push-up test can be used to find amplitude of accommodation. The distance is measured from the patient's face or spectacle plane? How do you convert distance to amplitude of accommodation?
*spectacle plane*; 100/cm
rare, uncontrollable saccades that occur at random and interfere with fixation; a corrective saccade is necessary to restore foveal fixation of the object of interest; <10 degrees movement (if >10 degrees, they're called ____________________)
*square-wave jerk*; macrosquare waves
Box: BOTH gradient AND calculated AC/A's are what type of AC/A? Why? What is the other type of AC/A, and is it usually larger or smaller than these?
*stimulus AC/A ratios*; we ASSUME the patient is accommodating equal to the stimulus, not actually measuring their accommodation! *response AC/A* determined by measuring accom, usually LARGER AC/A because of lag (lower bottom #)
Von Graefe phoria is a dissociated test that allows for determination of the *presence, direction, and magnitude* of an eye deviation. Is it objective or subjective? Can it determine a phoria from a tropia?
*subjective*; NO! (because dissociated)
*Saccades*: Visual information regarding target position is first sent from the eyes to the ______________________, which then sends information to the cortex. Most saccades are then initiated by the _____________________________________, though the _____________________ also helps to initial saccades.
*superior colliculus*; *CONTRALATERAL frontal eye fields*; *occipitoparietal junction*
the point where the muscle tendon FIRST makes contact with the globe
*tangential point*
*What does the blur point represent when performing smooth vergences?*
*the limit of FUSIONAL vergence*
*What does the break point represent when performing smooth vergences?*
*the limit of fusional AND accommodative vergence*
Where will the vertical line be displaced in after-image testing of a patient with a right esotropia and normal correspondence?
*to the left* (displaced where the eye points, DIFFERENT from crossed/uncrossed!!)
describes the eyes' position of rest at distance without a stimulus to convergence or accommodation; clinically it's measured as the best-corrected *distance phoria*; i.e. *physiological* position of rest
*tonic vergence*
Box: Patients should initially view *__________________ diplopia* before measuring Von Graefe phorias in order to avoid a stimulus to convergence that could alter the phoria.
*uncrossed*
type of ARC when the *angle of anomaly is LESS than the objective angle*
*unharmonious ARC*
*Incycloduction* or incyclotorsion is a rotation about the y axis such that the _____________ portion of the eye tilts inward (toward the nose)
*upper*
disconjugate eye movements in which the two eyes move in *opposite directions*
*vergences*
Pursuits are technically only ___________________ (voluntary or involuntary).
*voluntary* (in contrast to saccades, both invol and vol) (though very few people can actually do without a moving stimulus!)
What are the expected findings for MEM?
+0.25 to +0.50
symptoms of abnormalities with saccades
- *reading* problems (loss of place, slow, poor comprehension, short attention span) - difficulty copying or doing math
What tests should be considered if pursuit dysfunction is suspected?
- NSUCO oculomotor test for pursuits - Groffman tracings
What tests should be considered if saccadic dysfunction is suspected?
- NSUCO oculomotor test for saccades - Developmental Eye Movement test - Readalyzer
A patient has a normal 0.5mm nasal angle lambda, in each eye. 1. If the corneal reflex in this patient is displaced temporally when binocular, should you add or subtract angle lambda from the gross eso deviation? 2. What about if the angle is displaced nasally (so exo)?
1. *ADD angle lambda* to eso deviation 2. *SUBTRACT angle lambda* from exo deviation
1. What is the test in which the patient is asked to call off a series of numbers as fast as they can without using a finger to help with tracking? 2. The first series are arranged in vertical columns to determine the patient's random automaticity of naming (RAN). Then the second series of numbers are arranged in horizontal columns and assess both RAN and _____________________. 3. What are two similar tests?
1. *Developmental Eye Movement (DEM) Test* 2. *saccades* 3. *King-Devick* and Pierce saccade tests
What are the steps in assessing a new onset *binocular diplopia*?
1. *Establish comitancy* with versions, cover test, and subjective testing (e.g. Maddox, Red lens, or Hess-Lancaster) 2. If incomitant, perform *forced ductions* to differentiate between muscle restriction and palsy (may also perform regular monocular ductions, as palsy will be easier to overcome when monocular) 3. If it's a muscle palsy and has vertical component, perform Park's 3 step
What are the three types of *Duane's Retraction Syndrome*? Which is the least common? Which ones are associated with *globe retraction and narrowing of the palpebral fissure with aDduction*? Why?
1. *Type 1* - Limited ab*D*uction (must be differentiated from a CN 6 palsy) 2. *Type 2* - Limited a*DD*uction (least common) 3. *Type 3* - Limited ab*D*uction and a*DD*uction *ALL* of them; because of violation in Sherrington's law (*CN 3* goes and innervates both *MR AND LR*) "Count your D's!"
1. What is required to diagnose *Post Trauma Vision Syndrome*? 2. How is it treated?
1. *VEP* 2. Either *Binasal occlusion* or *2 BI prism over each eye* to decrease the degree of binocular processing and reduce symptoms
1. All the "excess" disorders have what? What Tx will be best for them? 2. All the "insufficients" have what? What Tx will be best for them?
1. *high AC/A; spherical lenses* 2. *low AC/A; prism or VT*
Box: Two subsets within accommodative insufficiency: 1. _________________ - normal accommodative testing that fatigues with repetition 2. _______________________ - pathological or pharmacologic causes for reduced accom
1. *ill-sustained accommodation* 2. *accommodative paralysis*
1. What does a *comitant deviation* indicate with a new onset binocular diplopia? 2. What does an *incomitant deviation* indicate with a new onset binocular diplopia?
1. *indicates it's probably a decompensated phoria* 2. *muscle restriction* or *muscle palsy*
1. *Damage to the RIGHT frontal eye field would result in impaired saccades towards the _________________*, resulting int the eyes *turning towards the ____________________*. 2. Damage to the *superior colliculus* causes a change in the ______________________ and ______________________ of saccades. Note: All of these effects are usually transient, and disappear within a few weeks.
1. *left* (OPPOSITE the lesion); *right* (TOWARDS the lesion) 2. *velocity*; *accuracy*
Box: 1. *Plus lenses indirectly test what?* 2. What about *minus lenses?*
1. *positive fusional vergence* 2. *negative fusional vergence* "BIM BOP" => do the same thing
*Fixation disparity curves*: Type 1 - _________________ shaped Type 2 - ____________ disparity Type 3 - _____________ disparity Type 4 - ______________ binocular system
1. *sigmoidal* 2. *eso* 3. *exo* 4. *unstable*
1. What is the minimum amount of accommodation someone should have? 2. What is the average amount?
1. 15 - age/4 2. 18.5 - 0.3(age)
*Congenital (infantile) nystagmus*: 1. Either present at birth or occuring before the age of ______, and affecting ________________ 2x as much 2. Often horizontal, conjugate, and is what kind of waveform? 3. About 40% are due to what? 4. The remaining 60% (so MOST of them) are caused by what?
1. 6; males 2. jerk OR pendular 3. defect in the AFFERENT pathway and poor image quality 4. defect in the EFFERENT pathway
*Convergence excess* must be differentiated from *pathologic causes* of accommodative/convergence spasms, such as what?
1. Inflammation: uveitis, scleritis 2. CNS Dz: syphilis, sympathetic paralysis 3. Pharmacologic: parasympathomimetic (pilocarpine, physostigmine), high doses of B1, sulfonamides
What are the two overall primary purposes of eye movements?
1. Move the eye so the fovea aligns with an object of interest (saccades, pursuits, vergences) 2. Hold images in place on the retina (fixation system while head is motionless, VOR during short motions of head, optokinetic system during prolonged head movements)
What tests tell us... 1. How much accommodation is present? 2. How accurate is the accommodative response? 3. How flexible is the accommodative system?
1. Push-up, pull-away, minus lens test 2. MEM or Nott's, BCC, NRA/PRA 3. Mono and bino accom facility
1. What type of waveform is *latent nystagmus*? 2. Is the fast phase toward the occluded or fixating eye? 3. It's associated with what condition?
1. jerk (which increases when one eye occluded) 2. fixating eye 3. *essential infantile esotropia* and *amblyopia*
Box: 1. As a general rule, a patient with a head turn due to an incomitant deviation will point their face in the direction that corresponds to what? 2. The head will tilt ___________ the side of the lesion in an SO muscle palsy. 3. The head will tilt ____________ the side of the lesion in an IO muscle palsy.
1. the field of action of the affected muscle 2. AWAY from 3. TOWARDS
By 3 yo, how long should a patient be able to fixate on a target? What's a normal length of each fixation while reading?
10 secs; 200-250ms
In *vergence facility testing*, a ____________ combination flipper is used. What are the expected findings in 1 minute?
12BO/3BI; *15 cycles/min*
Pursuits occur with a latency of approximately __________ msec and a velocity of _____________ deg/sec. Thus, they have a faster ______________ than saccades but a slower __________________.
130 msec; 50 deg/sec; latency; velocity
A score on the *Readalyzer* (which tracks eye movements) that's below the _______ percentile is considered evidence of what?
15th; *saccadic dysfunction*
What are the tests for *ARC*?
After image test Bagolini lenses
On a fixation disparity curve, where is BI, eso, BO, and exo?
BI left BO right Exo down eso up
The last step in the Park's 3 step of tilting the head to see where the hyper is worst is also called what?
Bielchowsky's head tilt test
What are the expected findings for accommodative facility testing? (ages 13-30)
Bino: 8 cpm Mono: 11 cpm
How is modified thorington different from maddox rod?
Both dissociated, subjective, and used to determine and measure phorias, and BOTH use maddox rod! But modified thorington actually has a scale on it, so you don't have to measure it with prism; in contrast, you have to prism neutralize Maddox rod until they report the line going through the center
What tests can determine the magnitude and direction of the positive and negative fusional vergence ranges at distance and near?
Direct tests: - *Smooth vergence* - Step vergences - Vergence facility Indirect tests: - NRA/PRA - BCC - Binocular accom facility - MEM retinoscopy
What are the *expected findings at distance and near for cover test*/phorias?
Distance: *0 - 2 exo* Near: *0 - 6 exo*
Box: What test can be used to diagnose eccentric fixation?
Haidinger's brush
the line passing from the fixation point to the fovea, and passing through the center of the pupil
Line of sight (LOS)
List the tests for fixation disparity. Which one is the most common and least expensive? In all of these, the right and left eye are viewing two separate images, but in the presence of fusion locks. They all require the patient to wear what?
Mallet unit AO vectographic slide Bernell lantern *Wesson fixation card* Sheedy disparometer polarized glasses
Box: What is a *positive* forced duction test?
Means that when you asked the patient to look in the direction of restricted movement (when evaluating incomitant deviation), the eye *DID NOT MOVE*, indicating the patient has a muscle *restriction*. A *negative* force duction test indicates it is a muscle *palsy*.
Homonymous hemianopsias are most commonly treated with what?
Peli lenses (one above, one below eye)
What type of instrument are two vertical lines deliberately misaligned, and the examiner gradually reduces the amount of prism offsetting the vertical lines until the patient reports their single?
Sheedy disparometer (opposite to the Wesson card, the two vertical lines truly remain separated, but they APPEAR to be aligned)
True or false. Acuity is usually *minimally affected* by homonomyous visual field defects.
True
Box: True or false. The OKN drum can be used as a gross method of measuring VA in infants.
True! A positive OKN response denotes a VA equal to or better than the corresponding VA size of the drum stripes; however, a negative response is inconclusive (though decreased VA and/or parietal lobe lesion should be considered)
Box: *What are the tests for eccentric fixation?*
Visuoscopy Haidinger's brush (uses birefringence) Maxwell's spot Monocular Hirschberg
What are the tests for *sensory status*?
Worth 4 dot Stereopsis
Will a vertical phoria affect fusional vergence ranges?
YES! Will have reduced PFV AND NFV, reduced vergence facility BO AND BI, and vertical vergences may either be constricted or larger (if long-standing)
What is a Maddox rod?
a series of stacked cylinders
What does the 4 BO test detect?
a small central suppression scotoma secondary to a *microstrabismus* (typically microesotropia)
Box: What kinds of conditions may lead to poor image formation on the fovea with a subsequent congenital nystagmus? (40% of congenital nystagmus, AFFERENT)
aniridia albinism achromatopsia optic nerve hypoplasia optic atrophy congenital cataracts
Is monocular or binocular accom facility testing performed first?
binocular (if fine, then both accom and vergence fine)
How should vision testing be performed differently in a patient with a TBI?
binocular testing should be performed in *free space*
Which will be greater, the calculated or gradient AC/A? Why?
calculated because of *proximal vergence*
Box: A microstrabismus is defined as what?
deviation *less than 10^* not visible on CT or other tests
What is the most common non-accommodative BV disorder, affecting 3-5% of the population?
convergence insufficiency
What kind of waveform is *spasmus nutans* nystagmus? It is often accompanied by what other sign?
disconjugate, high frequency, low amplitude, pendular waveform ("shimmering") that often has a horizontal AND vertical component; accompanied by *head nodding* and in 50% of patients, head turns
Which non-strab BV disorder's main complaint is *intermittent diplopia*?
divergence excess
a *monocular* rotation
duction
What are the findings of fusional vergence dysfunction?
everything normal EXCEPT for reduced PFV AND NFV ranges at distance AND near
What is the *minus lens test*?
finds amplitude of accommodation by adding minus lenses over BVA in the phoropter until the patient reports first sustained blur at 40 cm... then ADD the amount of minus + 2.50 to account for WD (so in other words, you can find the amplitude of accommodation by adding +2.50 to the PRA)
the line passing from the fixation point to the CENTER OF ROTATION of the eye
fixation axis
What is the third most common non-accommodative BV disorder? (after CI and CE)
fusional vergence dysfunction
Box: In Bagolini lens testing, are the striations on the glasses like an "A" or "V"? What does the patient see? What does this mean an esotropia will look like?
glasses are an "A", so patient sees a "V" with right line from the right eye, left line from the left; thus, an esotrope would see an uncrossed big V, while an exotrope would see a crossed "A" (left line leg from right eye)
What are the four categories the NSUCO oculomotor tests are graded on?
head movement, body movement, ability, and accuracy (on scale of 1 to 5)
Box: In what case besides normal correspondence would a patient see a perfect cross from after-image testing?
if the patient has *eccentric fixation* at the same location as their harmonious *ARC* point (so eccentric fixation = objective angle = ARC)
When performing visuoscopy, where would the FLR be if the patient had superior eccentric fixation?
inferior (center of grid is superior when eccentric fixation is superior because they think they're looking at it with their fovea, so center of grid will be where their eccentric point is!) *eccentric point always = the center of the GRID*
*Convergence-retraction syndrome* is characterized by an intermittent __________ nystagmus with a fast phase that causes both convergence or retraction of the eyes: When the patient looks _______, the eyes move slowly downward, followed by a fast phase causing convergence and/or retraction (REPLACING the quick movement towards upgaze). This condition is often associated with _____________________ syndromes.
jerk; up; dorsal midbrain (e.g. Parinaud's!)
Box: If a patient has a stroke in the left side of the brain, the visual midline shift will be to the _____________, and yoked prism should have its base towards the ___________.
left (right hemiparesis and neglect, so midline shifted to left, always *AWAY* from paretic side); right
*Duane's Retraction Syndrome* is a congenital condition most commonly noted in the ________ eye (right or left) in ___________ (males or females). The cause is unknown, but theories include structural abnormalities of the muscles or an innervational issue of the abducens and oculomotor nuclei in the brainstem. Most likely, *CN 3* goes and innervates BOTH the _________ and _________.
left; females; LR and MR (violates Sherrington's law!)
On a Wesson fixation disparity card, while the patient wears polarized glasses, which eye sees the black arrow BELOW the line? Which eye sees the colored lines, aka nonius lines? What does it mean if the patient sees the black arrow pointing to a line to the left of the central red line?
left; right; eso fixation disparity
When performing Bruckner, you see unequal red reflexes. What could the eye with the *DARKER reflex* have?
media opacity higher uncorrected refractive error FIXATING eye in strabismus
What is *Sheard's criterion*?
states that *the vergence reserve must be at least TWICE the demand of the phoria* (BO blur for exo, BI blur for eso) To prescribe prism... *S = (2/3)D - (1/3)R*
What is *Percival's criterion*?
states that the *smaller fusional vergence reserve should be AT LEAST HALF the greater fusional vergence reserve* (reserve = BLUR; places the demand line within the middle third of the zone of clear, single, binocular vision) *P = (1/3)G - (2/3)L*
Box: What is the theoretical advantage of the *pull-away method* over the *push-up method* for finding amplitude of accommodation?
the pull-away method is thought to minimize the variability in the subjective interpretation of "first sustained blur" and avoids the effect of relative distance mag with the push-up test Nevertheless, studies have not found any difference!!
If the patient has an incomitant deviation, the deviation will be worse when looking in which direction?
toward the underperforming muscle (e.g. a CN IV palsy affecting the SO will cause a hyper that's worse with ADduction and depression of that eye!)
the line passing from the fovea through the NODAL POINT
visual axis
*Listing's plane* is the plane normal to the visual axis and passing through the equator of the globe and center of rotation of the eye when it's in primary position of gaze. It consists of a horizontal, or _____, and vertical, or ____ axis, rotations about which are called ________________ positions of gaze. ________________ positions involve looking in an oblique direction (rotate around the ____ axis).
x; z; *secondary; tertiary*; y
AB and ADduction are around what axis?
z axis
