Abnormal Visual Development Amblyopia

Question 1

What is amblyopia?

Answer 1

Amblyopia is a unilateral or infrequently
bilateral condition in which the best
corrected visual acuity is poorer than
20/20 in the absence of any obvious
structural anomalies or ocular disease.

Question 2

What are the 3 causes of amblyopia?

Answer 2

Anisometropia

Strabismus (the earlier the onset the more damaging - Only CONSTANT strabismus will yield amblyopia)

Form deprivation (congenital cataract, ptosis, etc. Things that will affect normal vision)

Question 3

In hyperopia, what are the amblyogenic factors?

Answer 3

Greater than +1.00D anisometropia

Greater than +5.00D isometropia

Question 4

Which causes the most severe form of amblyopia, monocular or binocular deprivation?

Answer 4

Monocular as this will change cortex and cause morphological changes. Spatial frequency suffers. If remove congenital cataracts at 4-6 months old, VA will be 20/400 OU. If removed before 2 months of age, 20/40 deprived eye with rigorous patching.

Binocular will only cause mild amblyopia and if congenital cataract is removed at 4-6 months old, VA will be around 20/50 OU

Question 5

What is the most common forms of amblyopia?

Answer 5

Strabismic and anisometropic. About 90% of all clinical cases.

Strabismic results in 20/60-80. Low to no Central Spatial Frequency (CSF) Loss

Anisometropic results in greater than 20/60. Always have CSF loss at high spatial frequencies

Question 6

In myopia, what are the amblyopgenic factors?

Answer 6

Greater than -8.00D Isometropia

Question 7

In Astigmats, what are the amblyogenic factors?

Answer 7

Greater than -2.50D Cyl in isometropia

Question 8

What is the BCVA of Isometropic Amblyopes?

Answer 8

20/50 though the range is 20/20 - 20/200 depending on refractive error

Question 9

Trivial: What is the axis of WTR astigmatism

Answer 9

Around the 180 meridian. Squinting will help pt see better.

Question 10

You would expect to see morphological changes in the primary visual cortex under which scenario?

Answer 10

A patient with monocular congenital cataract that was removed at the age of 6mo. - the cataract was taken out too late, and it was monocular.

Question 11

In amblyopic reading, what is the main cause of the deficit of vision?

Answer 11

Increased crowding effect, NOT reduced VA.

Clinical note: When testing VA, use a single letter or single line to decrease crowding effect.

Question 12

What is the monocular fixation for anisometropic amblyopes?

Answer 12

Centrally and unsteady

Question 13

What is the monocular fixation for strabismic amblyopes?

Answer 13

Eccentric (0.5 - 4 degrees) and unsteady