CO Ocular Motility Evaluation & Binocular Vision Assessment 1

Question 1

What is the primary purpose of the cover test in ocular motility assessment?

Accepted Answer

To detect misalignment or latent eye deviations.

Answer

The cover test is a fundamental diagnostic tool in orthoptics used to assess ocular alignment. By alternately covering and uncovering each eye, the orthoptist can observe any movement of the uncovered eye, indicating a manifest deviation (strabismus) or a latent deviation (phoria) that is present when binocular fusion is disrupted. This helps identify the presence and type of eye misalignment.

Question 2

Which cranial nerve is primarily responsible for lateral eye movement?

Accepted Answer

Abducens nerve (VI)

Answer

The abducens nerve (cranial nerve VI) innervates the lateral rectus muscle, which is primarily responsible for abducting the eye, meaning moving it away from the midline. Damage to this nerve results in an inability to move the eye laterally and can cause esotropia (inward turning of the eye). The other nerves control different eye movements or sensory functions.

Question 3

What condition is typically diagnosed using Hirschberg’s test?

Accepted Answer

Strabismus

Answer

Hirschberg's test is a quick and simple screening tool used to detect strabismus, or ocular misalignment. It involves observing the reflection of a light source on the patient's corneas. If the light reflex is not symmetrically centered in both pupils, it indicates a deviation in eye alignment, suggesting the presence of strabismus.

Question 4

What is the function of the superior oblique muscle in eye movement?

Accepted Answer

Depresses and intorts the eye

Answer

The superior oblique muscle is one of the extraocular muscles responsible for eye movement. Its primary actions are depression (moving the eye downwards) and intorsion (rotating the top of the eye inward towards the nose). It also has a secondary action of abduction (moving the eye outwards).

Question 5

Which test measures a patient’s ability to maintain binocular vision under stress?

Accepted Answer

Prism bar vergence test

Answer

The prism bar vergence test is specifically designed to measure a patient’s fusional vergence amplitudes, which is their ability to maintain single binocular vision while the eyes converge or diverge. By introducing prisms of increasing strength, the test assesses the limits of the patient's ability to overcome prism-induced diplopia and maintain fusion, thereby indicating their binocular stability under stress.

(CO) Certified Orthoptist Practice Test

(CO) Certified Orthoptist Practice Test

CO Ocular Motility Evaluation & Binocular Vision Assessment 1