Strabismus and Amblyopia Flashcards
What is the ratio of esotropia to exotropia?
1 case of exotropia for 3-5 cases of esotropia
Which gender has more exotropia?
females
When does exotropia have its onset?
35-70% begin within first 2 years of life
What percent of exotropia is intermittent?
85%
Why should you be cautious in infants/young children with constant unilateral exotropia?
up to 70% is a neurological or ocular anomaly
T/F alternating exotropia is more common
true
16-52% of exotropes have an…
associated vertical component
What adaptations might be seen with exotropia?
close eye in sunlight, panoramic viewing
What are two goals of exotropia treatment?
improve stereopsis and improve cosmesis
What VT task is utilized for exotropia tx?
train convergence
Why might over-minus lenses be used for exotropia tx?
stimulates accommodative convergence, commonly used by OMDs, good short term until child old enough for tx, longterm wean off minus if good control
What amount over-minus is used for exotropia tx?
1-4D over cycloplegia
What does BI relieving prism do?
facilitates fusion with exotropia (does not fully correct)
How many hours a day is alternate patching used?
3-4 hrs, less benefit in older kids as compared to younger
What is the most common surgery for exotropia?
bilateral lateral rectus recession, then unilateral resect/recess
What magnitude of exotropia might surgery be done on?
15+ prism diopters
What should the acuity of exotropia be?
20/20
When the eyes are aligned during exotropia, what should the stereopsis be?
+ forms, decent Randot
When the eyes are deviated with exotropia what will the stereo acuity be like?
worse or no stereopsis
What is consecutive exotropia?
exotropia after surgical treatment for esotropia or after plus correction for esotropia
What would confirm consecutive exotropia?
eyes are exotropic but patient acts like esotrope, findings may not make sense aka uncrossed diplopia or amblyopia
What is the natural history of exotropia?
it improves over time quantitatively and qualitatively
What did PEDIG find in regards to untreated intermittent exotropia?
15% got worse but this is likely an overestimate
What are the concerns of using over-minused lenses as exotropia tx?
overminusing myopes leads to a risk of worsening myopia progression
What does a bilateral lateral rectus recession do?
moves the insertion back/posterior
What are three forms of esotropia?
infantile/congenital, accommodative and non-accommodative
What are the three subcategories of accommodative esotropia?
refractive, partially refractive, non-refractive
What is the onset of infantile esotropia?
birth to 6 months
57% of infantile esotropia is variable under ____ months
4 months
What are characteristics of infantile esotropia?
large angle, IOOA, DVD, latent nystagmus, refractive error >+3D, amblyopia
What counts as a large angle in esotropia?
greater than 40 prism diopters
What percent of children with large angle esotropia have >40D?
50%
What is the onset of DVD?
after age 2 or years after surgery, in 51-90% of infantile esotropia
What is latent nystagmus?
nystagmus after occlusion
How common is amblyopia in infantile esotropia?
50%
What is refractive accommodative esotropia?
esotropia within 10 prism diopters that has complete resolution with full RX
70% of refractive accommodative esotropia has a magnitude of deviation between…
11 and 45 prism diopters
What refractive error is typical in refractive accommodative esotropia?
+2 to +6D
What EOM is most likely the motor cause of refractive accommodative esotropia?
35% inferior oblique over-action
What is partially accommodative esotropia?
incomplete resolution with full hyperopic correction… difference in magnitude of deviation sc and cc yields residual component
How many of those with ET have partially accommodative esotropia?
33%
What are characteristics of partially accommodative ET?
constant, primarily unilateral, amblyopia common
What is non-refractive accommodative esotropia?
convergence excess esotropia
What percent of ET is non-refractive accommodative?
5%
What is the magnitude of deviation in non-refractive accommodative ET?
minimal at distance and 10 prism diopters or greater at near
What is the typical refractive error of non-refractive accommodative ET?
minimal hyperopia
What is the onset of non-accommodative esotropia?
6 months-2 years
What is the typical magnitude of deviation of non-accommodative esotropia?
30 to 70 prism diopters
What is the prevalence of ocular disease in non-accommodative esotropia?
11% retinoblastoma
Which ET has a better prognosis for binocular vision development?
non-accommodative esotropia
T/F diplopia may be present in non-accommodative esotropia
true
What are common esotropia treatments?
refractive error correction, prism, VT, or surgery
What is the refractive error correction for esotropia treatment?
plus, cycloplegic refraction is indicated
Is VT harder for esotropia or exotropia?
esotropia… harder to diverge the eyes
What are surgery options for esotropia?
bilateral medial rectus recession, and bilateral lateral rectus resection
What is the AOA definition of amblyopia?
poorer that 20/20 in the absence of any obvious structural anomalies or ocular disease
Those with amblyopia may have decreased…
fine motor skills and luminance perception
What is the amblyopia syndrome definition?
poor visual acuity plus spatial distortion, poor accommodation, decreased constant sensitivity, poor tracking and poor monocular fixation
What are contour interactions?
first and last letters of the chart are easier and single letter is easiest
What is the critical period for amblyopia development
1st 8 years of life
What are the functional amblyopia categories?
refractive, strabismic, both, image degredation, and 90% aniso/strab/combo
What are the two subcategories of refractive amblyopia?
isoametropic or anisometropic
T/F those under 7 years have more amblyopia than those under 3 years
true except strabismus is higher in younger than 3
What are physical obstruction examples that cause image degredation?
cataract, ptosis, hyphema, prolonged patching or occlusion
Does unilateral or bilateral congenital cataracts have a better prognosis?
bilateral
What is organic amblyopia?
not true amblyopia, due to structural anomalies of the eye or brain independent of sensory input
What are examples of structural anomalies that lead to organic amblyopia?
optic atrophy, optic nerve hypophemia, macular scar, anoxic occipital brain damage
What is the isoametropic hyperopia magnitude?
> +5D
What is the isoametropic myopia magnitude?
> -8D
What is the isoametropic astigmatism magnitude?
> 2.50D
What is the anisometropic hyperopia magnitude? AOA/AAO
> 1D/>2D
What is the anisometropic myopia magnitude? AOA/AAO
> -3/>-3
What is the anisometropic astigmatism magnitude? AOA/AAO
> 1.50/>2.00
Strabismus has poorer VA than ____
refractive amblyopes
What was the inter acuity difference in the amblyopia treatment studies?
3+ lines in ages 3-7
When should you consider contact lenses in anisometropic amblyopia treatment?
> 5D difference
When might you use a bifocal in a treatment plan?
if deviation is greater at near than distance
T/F treatment for amblyopia is better than no treatment
true
If VAs are 20/40-20/80 how often do you patch?
2hrs/day
If VAs are 20/100-20/400 how often do you patch?
2-6 hrs/day
When should you reassess a treatment plan for amblyopia?
8-12 weeks
Why might you use atropine 1%?
weekend as effective as daily atropine and patching
T/F bangerter foils are just as effective as patching
true
T/F teenagers are too old to treat
false, ages 13+ did well if no prior treatment
How much improvement is found in teenage treatment of amblyopia?
25% of teenagers had 2 lines of improvement
How often is there regression in amblyopia treatment?
24%
What causes a greater possibility of patching treatment regression?
greater in 1st 13 weeks after discontinuing patching and greater if abrupt discontinuation
What activities can be done while patching?
fine motor type activities like drawing, leggos, mazes, video games, eating
What are examples of activities one should not do while patching?
not riding a bike, not doing homework
What are vision therapy treatments for amblyopia?
accommodation, vergence, and antisuppression therapies
What was the result of dichoptic video games?
after 8 weeks VA improved 2 lines, after 10 hours stereopsis improved by factor of 4 (no improvement in patching)
What did the PEDIG study find in relation to dichoptic video games vs patching?
16 weeks iPad 1hr vs patch 2hr, both improved especially in ages 5 to 7, VA better in patching
