amblyopia\ Flashcards

Question

Amblyopia **Refractive** Anisometropia vs Isometropia _Dissimilarity of retinal images_ due to changes in _clarity, size, and contrast_ **Suppression**

Answer 1

**ANISOmetropic refractive amblyopia**: ## Footnote * **Uncorrected high UNIlateral refractive error** that is present **early in life**, one eyes gets the advantage * **VA = 20/80** or better, _milder or more superficial amblyopia_ than strabismus * **Hyperopic anisometropia**, more amblyogenic - because _accommodation is symmetrical_, more hyperopic eye blurred more at _BOTH distance and near_ * **Myopic anisometropia**, each eye has dominance (one at distance,the other at near) **ISOmetropic refractive error** * **significant BIlateral refractive error,** disrupts _overall development_, **no** shifts in ocular dominance columns or changes in the LGN * VA = 20/30 and 20/70 * Myopia vs hyperopia vs astigmatism * **NO Suppression** A**niso/isoametropia , the magnitude of RE** can predict the **severity** of **decreased VA** and the **depth of amblyopia**

Answer 2

“**meridional amblyopia**” if just the **astigmatism** is causing the amblyopia * **Recognition acuity** shows **overall decrease E** has horizontal and vertical components * **Grating acuity** shows a deficit **predicted by the axis** * Magnitude and axis determine amblyogenic potential (oblique \> ATR \> WTR) Horizontal meridian = vertical image Vertical meridian = horizontal image o Ie. plano -4.00 x180, the horizontal axis is clearer, therefore, the vertical image would be clearer **The problem 180 = Vertical Clearer** o Note: meridional and isometropic amblyopia are the **_mildest forms of amblyopia_**

Answer 3

There is a strong **linear relationship between 1-5D of anisometropia** 5D of aniso approaches 100% chance of IOD (intraocular acuity difference) of ≥ 2 lines **With anisometropia:** o **\>2D of SE aniso** →**40x** more likely to get an IOD & decreased acuity in 1 eye **With isometropia:** o Not as likely to see bilateral decreased VA o \>4D hyperopia in least hyperopic eye →11xmore likely to have bilateral decreased VA

Answer 4

FORM DEPRIVATION AMBLYOPIA * **Congenital or very early acquired degradation of visual stimuli** * Physical _obstruction along the visual axis_, prevents eye and _brain from forming connections_ * **Causes:** * Congenital cataracts * Ptosis * Corneal opacity * **Complete** vs. partial obstruction * **Unilateral** vs. bilateral (easier to treatment, simply slower) * Time of onset: Critical Worse * Duration of onset * Lapsed time before treatment **Latrogenic** **Amblyopia** from occlusion treatment (ie. patching all day, don’t

Answer 5

**ORGANIC AMBLYOPIA** ## Footnote * **Irreversible by treatmen**t, secondary to _not obvious structural changes_ * Ex: high myopes with mal-oriented PRs * toxic amblyopia (lead poisoning) * nutritional amblyopia (alcohol abuse) **IDIOPATHIC AMBLYOPIA** * decreased vision with **no strabismus, significant RE or episode of form deprivation** – no amblyogenic factors * Responds to treatment, but then shows regressio * **Transient amblyogenic factor?** * Constant strabismus early in life that resolved * High anisometropia as a kid that emmetropized **HYSTERICAL/PSYCHOGENIC AMBLYOPIA** * VA loss due to an **emotional problem** * typically _bilateral_ **VA loss 20/70-20/200** * females ~8-14yo **Tubular fields** peripheral vision same even when you vary the distance

Answer 6

• **Expected response from malingerers** * Color vision – all plates wrong * **4BO test – normal fusional response, objective** * **Retinoscopy** – minimal Rx (even cycloplegic), but significant improvement with spectacles * **Cover test – no problem seeing fixation target** * Stereopsis – unpredictable, but VA may improve with polaroid glasses

Answer 7

1. **Amblyopia is a diagnosis of inclusion and exclusion** – rule out _ocular disease_ and _document_ cause of amblyopia 2. **Label the specific type of amblyopia** 3. **Diagnosis must make sense in severity** – the depth (severity of acuity loss) of amblyopia depends on several factors including cause, onset, previous treatment and compliance 4. **Response to treatment is part of the diagnosis** – once treatment is started, amblyopia usually improves and should never get worse

Answer 8

* VA – **near AND distance VA should be equally reduced** * Check binocular VA to compare * **Pinhole expected endpoint** with refraction * Cover test – correct sized target, **2 lines above amblyopic eye** * Stereo – Get **baseline** to monitor improvement (trying to improve ***global stereo)*** * Fixation status * **Refractive error** – OBJECTIVE retinoscopy for peds * CYCLO for: full anisometropia and astigmatism * **Cyclorefraction**= **2gtt of1 % cyclopentolate separated by 5 min.** **Cycloplegic** – *minimal dilation* (only paralysis of accommodation), therefore, used in *conjunction with tropicamide* Functionla testing at followm up if RX prescribed

Answer 9

**Return Visit after Rx Wear (check compliance of glasses)** * Ensure **compliance** with glasses * **LENSOMETRY!** * Repeat **VA** * Dry retinoscopy over Rx * Repeat cover test * **Repeat stereo** * **Local** – _monocular cues_, easier * **Global** – _requires polaroid spectacles_ * Repeat fixation status **Subsequent Visits** * History probing **compliance** * Repeat 1-5 to monitor for improvement at every visit **\*\*\*Repeat cyclo before all Rx changes or if improvement stalls**

Answer 10

Optical correction Occlusion **evidence-based approach to managing amblyopia** * Prescribe an Rx if necessary. * Consider patching or some type of occlusion therapy * Expect improvement every 3 months **Amblyopia: Benifits of treatment** * **Functional impact** + treatment success rates of 60-70% * **1.2 to 10x increased lifetime risk of serious vision loss** in the fellow eye from disease or injury o Note: The **5-year cumulative incidence of bilateral visual impairment** (BVI – worse than 20/100 in the better seeing eye) **is significantly increased in patients with amblyopia** compared to non-amblyopes § *Non-amblyopes become more susceptible to BVI w/ age*

Answer 11

**Patching:** * Full time vs. part time (6 hours) patching for **severe amblyopia = No difference in VA** * Part time (6 hours) vs. minimal time (2 hours) patching for **moderate amblyopia = No** **difference in VA** **The Optical Correction** * provide **clearest retinal image possible** in each eye and **equalize the RE** between the eyes * **cycloplegia: baseline** – more reliable findings * rely on OBJECTIVE testing **Prescribing for Anisometropia** **FULL anisometropia** **FULL astigmatism** Cut hyperopia EQUALLY but not \> 1.5D residual **Glasses be worn before prescribing occlusion + expected improvement** 10-12 weeks.. **3 lines in 3 mos**

Answer 12

**Full Correction** ## Footnote * **Glasses be worn** before prescribing occlusion and expected improvement. * **_10-12 weeks.. 3 lines in 3 mos_** * **With glasses alone**, patients improved VA by ~2-3 lines on average after 3 mos * 1/3 of children did not require further treatment intervention * **Strabismic and strabismic-aniso amblyopes** treated with optimal optical correction * improved 3 lines in 3 months for both groups * **Monitor acuity (every 2-3 months)** until there is no significant improvement for at least 2-3 consecutive visits **Patching** * Clinical recommendation: **Part time occlusion** (in children 3-8yo) of at least 3-4hours/day is as effective as longer amounts of occlusion * 3-4hours **do NOT need to be consecutive** * **2-3 lines of improvement in3month** * _Majority of improvement_ takes place by**14weeks** * Compliance ist he major obstacle

Answer 13

**Compliance**: The extent to which patient **behavior matches the prescribers recommendations** ## Footnote **Concordance:** **Agreement that is reached** after negotiation between a patient and healthcare provider that respects the beliefs and wishes of the patients in determining whether, **when and how medicines are to be taken** Compliance - allow to explain expected outcome = Better treatment * **Poor compliance** * Parents not understanding treatment/condition * No improvement * Social and educational difficulties * Skin irritation Note: stress on the family is the largest obstacle to good compliance

Answer 14

* Compliance with patching hours was 44% * **Longer treatment** times led to **worse compliance** * **Increased visit frequency** led to **better compliance** * **Weekday** compliance **better t**han weekend IMPROVE * Educational materials aimed at the parent and child * Reward Calendar * Fun Patches

Answer 15

Bangerter Filter ## Footnote * Sticker **different densities** on the back of RX * **Scattered blur** like a cataract, decrease VA from 20/30- 20/300 depending on filter * can decrease contrast after acertain point * _NOT the best option_ if the patient has **poor compliance** with glasses Study on Bangerter filters compared to conventional patching \***Bangerter filters are a reasonable option to consider for the initial treatment of MODERATE amblyopia** Atropine * Higher compliance * **First line of treatment** along with conventional patching; both are considered equally **effective for mild, moderate, and severe amblyopia** * _patching and atropine are equally effective_ **Reduced dosage (2x/week) appears to be as effective as daily atropine** **ClinicalRecommendation**: * Rx**1gtts,1%atropine ophthalmic solution daily** _until improvement noted_ and then reduce schedule * Follow up **1 week after initiation of atropine** and then **every 4-6 weeks after that** * careful refraction of better eye **20/20** prevent Iatrogenic Amblyopia * Recommend **hat and sunglasses for outside**. Patient’s pupil will be dilated 24/7 Opaque Contact Lenses * expensive and only reserved for **severe amblyopia** * high plus CL in **Moderate Amblyopia** * poses a higher risk of infection to good eye

Answer 16

* **younger, moderate amblyopes** will have increased likelihood of success, compared to older severe amblyopes * Children **\< 4yo responded more rapidly** and with **smaller doses of patching compared** to older children * 25% of all subjects improved with spectacles ALONE (all ages) * **Patching/atropine** was effective in the **7-12 yo group** * Patching was effective in the13-17yo group ONLY if there was no previous treatment (ie. never worn glasses or done patching before)

Answer 17

* **Levodopa/Carbidopa** (Sinemet® - Merck and Co) * **LEVODOPA**: Intermediate in the biosynthesis of dopamine, originally prescribed for Parkinson’s disease * **CARBIDOPA**: Peripheral decarboxylase inhibitor and prevents break down of levodopa * When given together (Sinemet), **INCREASE dopamine levels** (which can **_INCREASE plasticity)_** **Perceptual learning** * Concept that humans are capable of improving performance through practice * perceptual learning tasks that are specifically aimed at this network should result in **improved spatial vision and function** * **increased binocularity and stereo** * Conclusion: 68% of treatment group improved 2 or more lines _independent of age_ * The biggest **gains of acuity** were seen in **contrast sensitivity tasks** * **Video Game play** * Arousal and reward _may increase dopamine levels_ à increased plasticity of brain _significant improvement_ in the **dichoptic learning**, but not the **monocular. Binocular** huge improvement was seen in VA and stereo

Answer 18

1. Optical treatment * **3 lines in 3 months** * **1/3 resolv**e (milder anisometropic amblyopes with stereo at baseline) * every 4-6weeks until plateaus for 2-3 app 2. Conventional occlusion or atropine penalization (first line Tx) * **3 lines in 3 months** * every 4-6 weeks until plateaus for 2-3 app * **Conventional occlusion** – At least **3-4 hrs/day** recommended * **Atropine 1%** – **Daily** or **reduced schedule (2x/week)** depending on needs of patient ***(start daily and then reduce*** * 1 week f/up * **iatrogenic Amblyopia risk** / monitor good eye VA * Recommend hat and sunglasses 3. Compliance 1. Educational materials 2. More **frequent follow-up** visits 3. Lower doses to start, but consider increasing the non-responders 4. **Regression** after cessation of occlusion MONITOR * first 3 months * 1 year follow up 5. **Maintenance patching**: Regression 4x more likely in children not weaned off of patching 6. 3hr for 1 month, 2hr for 1 month, 1hr for1month

Answer 19

**Strabismus:** **Manifested deviation** from the **line of sigh**t – visual axes not aligned when **BOTH eyes are open** (\>1pd) **Phoria** is only seen when _one eye is covered_ **Strabismus**, whether constant or intermittent, at somepointwhenbotheyesare open, one of the eyes is deviated

Answer 20

Direction ## Footnote * Esotropia, exotropia, hypertropia, cyclotropia * **Recording**:(vertical) * **Tropia**, specify **vertical (hypo or hyper)** deviation by the **tropic eye** * **Phoria**, specify **HYPER deviation** * **Torsion** – SO = intorsion / IO = extorsion **“Inferior people extort money”** Laterality * **Unilateral or alternating (Better prognosis)** Laterality Control L constant EXOTROPIA example * **Unilateral strabismus** * Cover OD, stays out, only when OS is covered, OD is forced to fixate and will move in, when uncovered, **instantly deviates out** * **Loses before blink** (alternator with specific FIXATION PREFERENCE) * Cover OD, stays out, cover OS, OD is forced to fixate and will move in, when uncovered, **will deviate out again within a secon** * **Loses during blin**k (alternator with specific FIXATION PREFERENCE) * Cover OD, stays out, cover OS, OD is forced to fixate and will move in, when uncovered, will deviate out again until blink, in this case, **strong left fixation preference** * **Loses after blink** (alternator with specific FIXATION PREFERENCE) * Still a left fixation preference, but not as noticeable since it takes more blinks for the OS to recover and OD to become deviated again * **True alternator** * 50/50 OD, OS Frequency Constant or intermittent Frequency control ex Unilateral right exo\_\_\_ ? * **Phoria** * Cover OD, underneath deviates out, uncover, OD instantly refixates on the target * **Recovers before blink** (intermittent strabismus) * Cover OD, underneath deviates out, uncover, OD refixates within a second * **Recovers after blink** (intermittent strabismus) * Cover OD, underneath deviates out, uncover, OD refixates following a blink * **Delayed recovery after blink** (intermittent strabismus) * Cover OD, underneath deviates out, uncover, OD refixates following several blinks * **Constant strabismus** (when both eyes open, one eye is ALWAYS deviated) * Stays out indefinitely, only comes in when forced to fixate by covering OS, uncover **OS, instantly goes back out**

Answer 21

MAYO Scale – Intermittent Exotropia Control ``` 5 = **constant XT** when observing the patient (without dissociation) 4 = **XT \> 50%** of the time during 30 second observation (without dissociation) 3 = **XT \< 50%** of the time during 30 second observation (without dissociation) 2 = **no XT unless dissociated** (with occlusion); **recovered in \>5 seconds** 1 = **no XT unless dissociated** (with occlusion); r**ecovered in 1-5 seconds** 0 = e**xophoria no XT** unless dissociated (with occlusion); recovers in \<1 second ```

Answer 22

Dist vs Near ## Footnote * Determine treatment options and dist * _Differential diagnoses:_ * **ET larger at distance** more likely related to **pathology** (_do an MRI_ 6th nerve palsy * **ET larger at near** a more likely related to **hyperopia (Acc eso)** Magnitude: * Treatment = small enough for **fusional amplitude to control** * Psycho social factors * **Large enough to consider strabismus surgery**. * horizontal deviation is ≥ 12 Δ * Parks 3 Step * **R-L-R / L-R-L pattern with superior oblique palsy (CN4)** * Note: 1mm shift = 22 Δ * Psycho social factors * Observe At least**14.5Δ ET**, at least **8ΔXT (**more obvious small deviation) * **Asians**, esos more noticeable * **Caucasians** exos noticeable * **AfricanAmericans** , exos slightly more noticeable

Answer 23

Comitancy ## Footnote * **\< 5 Δ difference in magnitud**e of strabismus in **all positions of gaze** at specific testing distance * **Non-comitant deviations** generally of higher risk **/Pathalogical Strab** * Paretic * Restrictive * **Largest E(T)** in **right gaze** Most symptomatic * ***_Right 6th nerve palsy (LR)_*** * Horizontal and vertical strabismus, **RH(T**) largest in **left gaze** and **right head tilt** * ***_Right SO 4th Nerve_*** Ductions vs. versions * **Versions = binocular** eye movements in the same direction * **Ductions = monocular** eye movements (cover one for EOMs) * **Movement** = Tropia / **No movement** = Palsy * **Recording**: (+) overaction, (-) underaction * **scale of 1 to 4** – can’t cross the midline, **it’s a -4** **Brown’ssyndrome** = SO restriction Both eyes **Psychogenic convergence spasm** = eyes want to converge when both eyes are open * Patient can **finally abduct** when the target gets so far that the **nose blocks it** * **Mimics an abducens palsy** until you get to the point where it is a monocular duction * **Dysconjugate gaze** beating nystagmus = endpoint nystagmus

Answer 24

TEST * **40cm** testing distance, **40cm separation** * **Evaluate** Initiation, velocity, accuracy – **10 cycles** Gain calibration * **Abnormal:** * **Slow saccades** / **lack of coordination** / **asymmetry** between the eyes is abnormal Note: **INO** mimics medial rectus impairment. When the eye tries to adduct towards the nose, **visible INO**, limited to the midline. _If one eye hits the target first in a saccade and the other eye slides along_, this is a **classic INO sign**

Answer 25

**Infranuclear pathway** * Shared by all pathways * **all 3 are abnormal**, problem infranuclear pathway **Tests to see which pathway is damaged:** * **Doll’s head**: Vestibular pathway * **EOMs**: Supranuclear pathway (*VOLUNTARY)* * SN - Brainstem - IN - Eye * **OKN drum**: Supranuclear pathway (*INVOLUNTARY)* * Can hold _vertically or horizontally_ * **Optokinetic nystagmus** involves **both infranuclear and supranuclear pathways** **EOMs abnormal** / Dolls head normal R/O Vestibular / **OKN abnormal** ***_Supranuclear problem_*** vs normal malingering

Answer 26

Test to detect **mechanical limitation of motion** _An attempt to move the eye forcibly in the direction of gaze limitation_ while the patient is _attempting to look in that direction_ (using an anesthetized swab) Subjective **(+) forced duction = restriction** **(-) forced duction = normal**, probably paralytic

Answer 27

**Important Characteristics of Adaptation** 1. **Age and onse**t of strabismus 2. **Duration** of strabismus 3. Comitancy (History of strabismic surgery, comitancy may change) 4. **Type of strabismus** * *Infantile ET constant \>40-50pd before 4-6mos*, _surgery consecutive XT ‘current presentation’_ As a clinician, you may not be privy to 1 and 2. 3 and 4 may change over time. So, being able to test for the type of adaptation can be a way of gaining insight into all 4 characteristics

Answer 28

1. **Close an eye** 2. Increase fusional amplitudes * **XT,** worse on **BO ranges (PFV) to contro**l (Not correct), requires more to compensate 3. Blind spot syndrome = ET only 4. **Non-comitancy** * cannot suppress, **compensate with head turn/tilt** 5. **Visual ignoring** * ****can not suppress, one image not on the fovea, will ignore the ‘blurry’ image, _more common with small strabismus_ or when VA is monocularly reduced * **Difficult if equal VA in both eyes**

Answer 29

**SUPPRESSION** * **Cortical** phenomenon * V**ariable / Active process** (recognition of issue, actively signal to resolve the issue with suppression) * **Respects laterality** * When *fixation alternates, suppression shifts* to the other eye * **Respects frequency** * ****Intermittent strabismic not at risk for amblyopia * **Depth of suppression** – variable * Suppression develops **under natural conditions.** * artificial environment = possible Diplopia **Bagolini density filter bar** **Degrades acuity of good eye** to force the patient to **see double**, equalizes the quality of the image on the good eye to see images of the bad ‘***how much degradation before the brain will no longer suppress the bad eye?’***

Answer 30

**ANOMALOUS RETINAL CORRESPONDENCE** * **BINOCULAR** conditions / **Cortical** phenomenon * ARC, shift in **visual cortex ‘remapping’**, gives non-foveal point principal *visual direction and motor value of 0* * Requires plasticity of visual system (**within critical period)** * **pseudofovea“F”** Play the role of the fovea, but still **not as clear as anatomical fovea** (highest density of cones) * Small **active focal suppression** of the physiological fovea F also occurs **Binocular conditions**, preference – **pseudofovea** **Monocular conditions**, preference – **anatomical fovea** * **IMPOSSIBLE to have global stereopsis** * will have **poor local stereopsis** * Strabismus must be consistent * **15-18pd deviation,** too large, too poor of optical quality * **\<6-8yo** (plasticity required) * **Objective angle**: Motor movement **cover test**, * True objective angle = (“F” - ef) + (ef - F) * **“F” to ef** = how much you’ll see on **cover test** * **Ef to F** = measured in **Visuoscopy**, distance between eccentric fixation point and anatomical fovea * ET, more commonly constant, **(+) due to nasal ef** * **Subjective angle**: Magnitude of strabismus that the **brain perceives the strabismus** to be. * 10pd constant left ET, the patient reports **seeing 4 dots** * **Subjective angle = 0** since they’re perceiving 4 dots **assumed ARC** **Bagolini Striated Glass** to assess fusion, suppression, and correspondence * perceives **no dissociation** * Eso = Uncrossed = “V” pattern * Exo = Crossed = “A” pattern

Answer 31

**MONOFIXATION SYNDROME** ‘Microtropia’ * Involves **small central suppression under binocular viewing conditions** * Clinical profile: * Reduced monocular acuity (20/25**-20/40)** * **Normal cover test** * **Local stereo is present, but reduced** (no global stereo) * Aniso may or may not be present * No AMBLYOGENIC refractive error * The Development of **Central Suppression** * Small esotropia(\<10pd) * **Closer to fovea** than ARC, therefore, **better resolution** * Development of **eccentric fixation occurs at the pseudofovea “F” = ef**

Answer 32

Harmonious ARC (mostcommon) ## Footnote * Subjective angle = 0 * objective angle = 15pd, subjective angle = 0pd, **normal “X” seen on bagolini**, NO percieved strabismus UnharmoniousARC § Rare * **REDUCTION** of diplopia * **Subjective angle is smaller** than objective angle * objective angle = 15pd, subjective angle = 5pd EX. **constant left ET**, but then with presbyopia it **decompensates** and gets larger, the **ARC has been previously remapped** ParadoxicalARC * DOES NOT resolve or reduce diplopia * Subjective angle is **larger** than objective angle * objective angle = 15pd, subjective angle = **20pd** • If the patient **had strabismus with harmonious ARC** and later had **surgery**, the diplopia becomes much worse

Answer 33

STEREO & FUSION: * Provides insight into: **Age of onset, frequency, and duration** * Can't **fuse prism** = won’t fuse with **surgery** either * **Testing sensory without motor** * Use prism – **move the image** to where the eye is to allow for **bifoveal fixation** * **Exo**, neutralize with **BI** § **Eso**, neutralize with **BO** * **Centration point** where **both lines cross at a random point in space** * **Synoptophores/Major Amblyopscopes** * Equipment to look at the angle of deviation and their binocular potential at a theoretical distance (fixation point) * Creates **simultaneous perception** of two images on corresponding points ‘superimposition’ * **Can be used to train an amblyopic eye**

Answer 34

Visual Acuity ## Footnote * Provides insight into: **age of onset, laterality, and frequency** * **Symmetric good VA binocularly** (ie.20/20 **intermittent** and/or **alternating** **20/20 with good stereo**: Intermittent (Since binocularity required to fuse) **20/20 with poor stereo:** Alternating (No fusion since never under binocularity) * Asymmetric poor VA monocularly * **Difficulty to restore binocularity** * Eye with decreased VA will drift out on its own even after surgery, might need retouch in 10+ years Refractive Error * Corrected Refractive error - **VA, alignment, and potential to fuse** * **Blur**, barrier to fusion * Correction, may improve stereo, but will likely not be perfect o Amblyopia risk factor \>2.50D ‘iso’ astigmatism Always start with correction of refractive error, then follow-up with reassessment of stereo/alignment and VA