ABO Binocular Vision & Strabismus

Question 1

The Hirschberg corneal light reflex test is primarily used to estimate the angle of which condition?

Accepted Answer

Strabismus

Answer

The Hirschberg test uses the position of the corneal light reflex relative to the pupil center to estimate the angle of deviation in strabismus.

Question 2

In esotropia, the deviating eye turns in which direction?

Accepted Answer

Inward (nasal)

Answer

Esotropia is an inward (nasal/medial) deviation of the eye, commonly called 'crossed eyes.'

Question 3

Which term describes a latent ocular deviation that is controlled by fusion and only becomes manifest when fusion is disrupted?

Accepted Answer

Phoria

Answer

A phoria (heterophoria) is a latent deviation kept latent by fusional vergence, only revealed by dissociation techniques such as the cover test.

Question 4

The cover-uncover test is the most reliable clinical method to distinguish between a tropia and a phoria because it:

Accepted Answer

Disrupts fusion, revealing any manifest deviation in the covered eye

Answer

When one eye is covered, fusional vergence is disrupted; a refixation movement of the uncovered eye upon removal of the cover indicates a tropia, while movement of the covered eye on cover removal indicates a phoria.

Question 5

A positive result on the Randot Stereotest indicates:

Accepted Answer

Bifoveal fixation and intact binocular vision

Answer

Passing the Randot Stereotest demonstrates bifoveal fixation and functional binocular vision with intact stereopsis.

ABO - American Board of Optometry Practice Test

ABO - American Board of Optometry Practice Test

ABO Binocular Vision & Strabismus