ABO Binocular Vision & Strabismus 3

Question 1

The AC/A ratio expresses the relationship between:

Accepted Answer

The amplitude of accommodation and the degree of convergence per diopter of accommodation

Answer

The AC/A (accommodative convergence/accommodation) ratio quantifies how many prism diopters of convergence are elicited per diopter of accommodation exerted.

Question 2

Microtropia (monofixation syndrome) is best characterized by:

Accepted Answer

A small-angle tropia with peripheral binocular fusion and central suppression scotoma

Answer

Monofixation syndrome (microtropia) features a small angle strabismus with a central suppression scotoma in the deviating eye but preserved peripheral fusion, giving reduced but measurable stereopsis.

Question 3

A hypertropia is defined as a vertical deviation in which the deviating eye turns:

Accepted Answer

Upward

Answer

Hypertropia describes an upward vertical deviation of the eye; the prefix 'hyper-' means above or higher.

Question 4

The Bielschowsky head tilt test is a critical diagnostic maneuver for identifying palsy of which cranial nerve?

Accepted Answer

Cranial nerve IV (trochlear)

Answer

In trochlear (CN IV) palsy, tilting the head to the affected side increases the hyperdeviation because the superior rectus (an intorter) acts as an elevator when the superior oblique is paretic.

Question 5

The primary purpose of a suppression scotoma in a patient with constant strabismus is to:

Accepted Answer

Eliminate diplopia by inhibiting the image from the deviating eye's fovea

Answer

Cortical suppression of the fovea of the deviating eye is an adaptive response to prevent diplopia (and visual confusion) caused by the misaligned eye.

ABO - American Board of Optometry Practice Test

ABO - American Board of Optometry Practice Test

ABO Binocular Vision & Strabismus 3