Lecture 3b: Diagnostic Drops, Cyclo-refraction, Presbyopia, and Potential Acuity

5 Types of Presbyopia

-1. Incipient: early → may or may not Rx -2. Functional: reduced accommodation becomes problematic → requires correction -3. Absolute: virtually no accommodative ability -4. Premature: accommodation ability becomes insufficient earlier than expected based on the pt's age -5. Nocturnal: near vision decreases at night in dim lighting conditions → increased pupil size and decreased depth of field

5 Measures of Potential Acuity

-1. Retinometry -2. Interferometry -3. Potential Acuity Meter -4. Potential Acuity Pinhole -5. Superpinhole

3 Types of Cycloplegic Drops

-1. Synthetics → Tropicamide/Mydriacyl → Cyclopentolate/Cyclogyl -2. Semi-synthetic → Homatropine -3. Natural (aka Belladonna alkaloids) → Scopolamine → Atropine

Determining the Add

-Amplitudes (but not necessary) -FCC: tentative add -NRA/PRA: balances the add -Age chart -Measure the distance needed and determine the power -Blur in/blur out

Acute Belladonna Poisoning

-Children: 10-30 mg (20 gtts of 1%) -Adults: 80-130 mg (160 gtts of 1%) → 1 gtt of 1% x 2 eyes = 1 mg

Uses of Cycloplegia

-Esotropia -Suspected latent hyperopia -Suspected pseudomyopia -Malingering/hysterical pts -Uncooperative/very young pts -Reduced VA with no pathology -Symptoms without significant RE -Anterior seg inflammation/post-surgical -Used in amblyopia -Used to aid in acceptance of new lenses -Used to treat myopia progression

Systemic Reactions of Cycloplegic Drops

-Hot as a Hare → fever, inability to sweat -Red as a Beet → facial flushing, vasodilation -Dry as a Bone → dry mouth, skin, inhibits exocrine glands -Blind as a Bat → cycloplegia -Mad as a Wet Hen → irritability/hallucinations, CNS toxicity

Adverse Reactions of Anesthetic Drops

-allergic reaction → contact dermatitis → Stevens-Johnson Syndrome: skin and mucous membrane disorder precipitated by various agents → surface keratopathy

Instillation of Anesthetic Drops

-always check VA first -do all testing that can't be verified after dilation (pupils, add determination) -check bottles twice -usually proparacaine first → kids may have a prepared spray → improves drug penetration → improves dilation -don't touch lashes/hold the cap -pt may vasovagal syncope → lower back, raise feet, open alcohol wipe over nose and have them cough

Cycloplegic Drops

-ciliary muscle → relaxes accommodation -iris sphincter → dilation

Mydriatic Drops - Phenylephrine

-concentration: 0.125%, 2.5%, 10% -sympathomimetics → alpha-adrenergic agonist -stimulate iris dilator (if only used for dilation, pupil will still react to bright light) -vasoconstrictor → blanches the conj (rule out episcleritis vs scleritis) -widens palpebral aperture -No cycloplegic effects -Max dilation: in 45-60 min -Duration dilation: 4-6 hours -Check BP (especially with 10%)

Anesthetic Drops - Benoxinate with Fluorescence

-concentration: 0.4% -used for Goldmann Tonometry -aka Fluress → Benoxinate + Fluorescein

Anesthetic Drops - Proparacaine

-concentration: 0.5% -esters chemical structure -prior to dilation drops and contact procedures -occasionally before VA if pt is in significant pain and unable to obtain VA without it -roughens epithelium → increase drug penetration

Cycloplegic Drops - Tropicamide

-concentration: 0.5%, 1% -rapid-acting, short duration mydriatic/cycloplegia → peak cycloplegia: 20-35 minutes → recovery: 6 hours -used during comprehensive ocular exam -1st drop produces variable cycloplegia → 2nd drop 5 minutes later gives reasonable cycloplegia -less than 2 D of residual accommodation -after 35 minutes, cycloplegia no longer reliable

Cycloplegia Drops - Scopolamine

-concentration: 0.5%, 1%, 2% -peak cycloplegia: 30-60 minutes -recovery: 3-7 days

Cycloplegic Drops - Cyclopentolate

-concentration: 0.5%, 1%, 2% -rapid-acting mydriatic and cycloplegic → peak cycloplegia: 25-75 minutes → recovery: 8 hours -commonly used in cycloplegic refraction for latent hyperopia, esotropia → children <1 yr: use 0.5% → children >1 yr: used 1% -residual accommodation: 1.5 D -retinoscopy should be performed 40-60 minutes after instillation -a second drop can be instilled

Cycloplegic Drops - Atropine

-concentration: 0.5%, 1%, 2%, 1% ointment -strongest cycloplegia and longest-acting → peak cycloplegia: 1-3 hours → recovery: 6-12 days -may use in case of ET in young patients -can be used during amblyopia therapy -can be used to aid in acceptance of new lenses -low dose used to prevent myopia progression (0.01%, 0.02%, 0.025%, 0.05%) -post-ocular surgery -ocular inflammation

Cycloplegia Drops - Homatropine

-concentration: 2%, 5% -peak cycloplegia: 30-60 minutes -recovery: 1-3 days

Standard Effects of Anesthetic Drops

-decreases reflex tearing -reduced blink rate -epithelial toxicity -tear film instability

Cycloplegia - Esotropia

-determine the accommodative component -Atropine is DOC for <4 y/o → use 1% solution TID for 3 days prior to appt → use 1% ointment BID for 3 days prior to appt (less systemic absorption/side effects) -many will used 1% Cyclopentolate first if it works → if not, try Atropine

Yasuna's Method of Residual Accommodation

-distance Rx in phoropter -add +3.00D OU -occlude one eye -target: 0.5 M @ 33 cm -add plus in 0.25D steps to blur -replace +3.00D OU -reduce plus in 0.25D steps to blur -dioptric difference (absolute value) → residual accommodation

Duane's Method of Residual Accommodation

-distance Rx in phoropter -add +3.00D OU -occlude one eye -target: 0.5 M @ 33 cm -determine near blur point → pull in and measure -determine far blur point → pull out and measure -difference between the 2 → residual accommodation

Procedure of Cycloplegic Retinoscopy

-focus on central reflex -dilated pupil produces a lot of aberrations -expect more plus -amount depends on pt → high: latent hyperope, pseudomyope, accommodative ET, accommodative spasm → low: myope, emmetrope -MPMVA

Amount to Prescribe - Latent Hyperopia

-have pt return post-cyclo exam to determine prescribing Rx, if pt is very young → push plus -amount of latency to add to dry: → 0 to +0.50D → 0D → +0.75D to +1.00D → +0.25D → +1.25D to +2.00D → +0.50D → > +2.00 → 1/4 latent amount

Facultative Hyperopia

-hyperopia that can be overcome by accommodation -within range of pt's accommodation

Absolute Hyperopia

-hyperopia that can't be overcome by accommodation -when a pt's hyperopia is higher than their amplitude of accommodation

Treatment of Hyperopia - Repeat Dry Refraction

-if more plus isn't accepted and they're symptomatic → dry at distance → wet at near (bifocal) -if more plus is accepted → Rx MPMVA (dry)

How can prescribing cause more problems?

-if pt is exophoric and a hyperope -if pt is esophoric and a myope

Amount to Prescribe - Myopes

-if wet ≤ dry → Rx dry -if wet > dry → have pt return post-cyclo, trial frame to push plus that they'll accept

Amount to Prescribe - Based on

-judgment, skill, experience -relieve symptoms -consider binocularity and accommodative status

Cycloplegia - Pseudomyopia

-low myopia -near point symptoms -fluctuating VA -accommodative spasms after near work -NRA > PRA -low amplitude

Retinometry

-measures the potential acuity of the retina/ON -type of acuity: Resolution Acuity -able to get through media opacities -useful when sending pts for cataract surgery → VA improved or not -useful for poor refraction results

Contraindications to Cycloplegic Drops

-narrow or closed angles -known allergy -iris-fixed IOL -down syndrome -pt needs near vision to function

MOA of Cycloplegic Drops

-parasympatholytic drops → anticholinergic/antimuscarinic -block the muscarinic receptors on ciliary muscle and prevent acetylcholine from binding -inhibits action of the iris sphincter

Function of Anesthetic Drops

-prevent the generation/conduction of nerve impulses by blocking sodium influx into the neural membrane -pH of surrounding environment can affect its actions -infectious debris changes pH to acidic → less effective

Retinometer

-projects diffraction gratings with different spatial frequencies onto the retina (Resolution Acuity) -Maxwellian presentation -only need a small window through the opacity -measures from 20/300 to 20/25 -wear specs if 6D of RE → can wear if even less

Cycloplegia - Latent Hyperopia

-pts complain of difficulty with near vision → headaches at near → difficulty with sustained reading -EP at distance -miotic pupils -high FCC -decreased amplitude for age -static has more plus than subjective -NRA > +2.50

Treatment of Hyperopia - Near Rx

-reading spectacles -bifocal → large segment with high placement just under pupil -recheck 2-4 months → may find more plus acceptance

Accommodation & Binocularity - Procedure

-repeat resting with subjective → near VA, amplitudes, FCC, NRA/PRA, CT, phorias/vergences -educate pts/parents -have them return for a follow-up for re-eval -may need to consider VT to resolve new problem

Prescribing Options for Presbyopia

-single vision → NVO and DVO -bifocals -trifocals with intermediate vision (1/2 bifocal) -occupational lenses → computer/piano lenses → add at the top of the lenses - pts look up for near work

Cycloplegia - Anterior Segment Inflammation

-stabilizes the blood aqueous barrier → NPE cells contain tight junctions, zonula adherens, and desmosomes -helps reduce the permeability of blood vessels → less leakage of white blood cells and protein (cells & flare) -stabilizes the iris -decreases possibility of posterior synechia

Pascal's Method of Residual Accommodation

-static at distance -static at ret plane -dioptric difference of the two is residual accommodation

How to Examine Presbyopia

-take a good history -know your pt's near demands → reading, reading music, lecturer, knitting, mechanics -once you've determined the need → determine the add

Vasovagal Syncope

-temporary loss of consciousness/posture -triggered by contact procedures, drops -Vagus nerve is overstimulated → results in dilation of peripheral blood vessels → decreased blood supply to the brain -signs/symptoms: pale, bradycardia, dizziness, clammy skin, nausea -treatment: stay calm, recline the pt/raise the legs, keep reclined for 15-30 minutes

Latent Hyperopia

-total amount of hyperopia compensated for by the tonicity of the ciliary muscle -can't be relaxed voluntarily or with plus lenses -uncovered during cycloplegia (wet-dry) -total hyperopia = manifest + latent -normal: 0 to +0.5D

Side Effects of Cycloplegic Drops

-toxicity -hypersensitivity (can occur in Down Syndrome pts) -allergy → itchy, red, swollen -angle closure → look at Van Herick angles -systemic reactions

Manifest Hyperopia

-uncovered during subjective refraction (dry) -can be relaxed by the pt through plus lenses -not correct by ciliary tone

Treatment of Hyperopia - Rx Options

-use cyclo for Rx acceptance during dispensing -follow up on your pts → wearing specs → looking for other binocular findings → pushing more plus

Cycloplegia - Myopia Progression

-use low dose Atropine to slow myopia progression -multiple concentrations are being studied and have shown to be effective (<0.5%) -children that have progressing myopia/family history of high myopia -try to prevent hight myopia/pathological → high: ≥-6.00 D RE or ≥26.5 mm axial length

Potential Acuity Pinhole (PAP)

-use pinhole on dilated eye -full room illumination -near card with line illuminated by transilluminator -pt holds the card at required distance → Wormington: 40 cm → Rosenbaum: 14 inches

Potential Acuity Meter (PAM)

-uses Maxwellian view optical chart to project a bright mini Snellen acuity chart -letter size: 20/400 to 20/20 -depends on the intensity of light reaching the retina (dense cataract worsens the results) → poor results if acuity is < 20/200 -requires approximate refraction -best on dilated pupil

Interferometer

-uses Maxwellian view optical system to produce interference pattern on the retina -the finer the pattern, the more macular resolution is required → the better the acuity -only 2% transmission is needed -best on a dilated pupil -a decimal reading is converted to Snellen acuity

Superpinhole

-uses a lightbox with LogMAR acuity -testing distance: 5 ft -pt should be dilated, wear their correction, room illumination should be dim, pinhole -if acuity is 20/70 or worse, something other than cataract is causing the decreased acuity

Residual Accommodation of Adequate Cycloplegia

2 diopters

Potency of Cycloplegic Drops

Atropine > Scopolamine > Homatropine > Cyclopentolate > Tropicamide