AOA Ocular Anatomy and Physiology 3

Question 1

The corneal endothelium maintains corneal deturgescence primarily through which mechanism?

Accepted Answer

Active ion pumping via Na+/K+-ATPase to move fluid from the stroma to the anterior chamber

Answer

Corneal endothelial cells use Na+/K+-ATPase pumps to actively transport fluid from the corneal stroma into the aqueous humor, counteracting the natural tendency of the stroma to imbibe water and maintaining corneal clarity.

Question 2

Horner's syndrome results from a lesion of which neural pathway?

Accepted Answer

Sympathetic pathway to the iris dilator and Müller's muscle

Answer

Horner's syndrome is caused by interruption of the sympathetic pathway, leading to ptosis (Müller's muscle), miosis (iris dilator), and anhidrosis on the ipsilateral side.

Question 3

Which layer of the tear film, produced by the meibomian glands, serves as the outermost layer and prevents evaporation?

Accepted Answer

Lipid layer

Answer

The outermost lipid layer, secreted by the meibomian glands, reduces evaporation of the underlying aqueous layer and stabilizes the tear film.

Question 4

The pupillary light reflex (direct and consensual) relies on which afferent pathway?

Accepted Answer

Optic nerve → pretectal nucleus → bilateral Edinger-Westphal nuclei

Answer

The afferent limb of the pupillary light reflex travels via the optic nerve to the pretectal nucleus in the midbrain, which projects bilaterally to the Edinger-Westphal nuclei, enabling both direct and consensual responses.

Question 5

Which of the following best describes the blood supply to the outer retina (photoreceptors and RPE)?

Accepted Answer

Choriocapillaris of the choroid

Answer

The outer retina, including photoreceptors and the RPE, receives its oxygen and nutrients by diffusion from the choriocapillaris of the choroid, as the retinal capillaries do not extend into the outer retinal layers.

AOA - American Optometric Association Practice Test

AOA - American Optometric Association Practice Test

AOA Ocular Anatomy and Physiology 3