Ocular Anatomy and Physiology Flashcards
7 cards from real AOA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Ocular Anatomy and Physiology flashcards as text
The corneal endothelium maintains corneal deturgescence primarily through which mechanism?
Answer: Active ion pumping via Na+/K+-ATPase to move fluid from the stroma to the anterior chamber
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.
Horner's syndrome results from a lesion of which neural pathway?
Answer: Sympathetic pathway to the iris dilator and Müller's muscle
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.
Which layer of the tear film, produced by the meibomian glands, serves as the outermost layer and prevents evaporation?
Answer: Lipid layer
The outermost lipid layer, secreted by the meibomian glands, reduces evaporation of the underlying aqueous layer and stabilizes the tear film.
The pupillary light reflex (direct and consensual) relies on which afferent pathway?
Answer: Optic nerve → pretectal nucleus → bilateral Edinger-Westphal nuclei
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.
Which of the following best describes the blood supply to the outer retina (photoreceptors and RPE)?
Answer: Choriocapillaris of the choroid
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.
The physiologic blind spot corresponds to which retinal structure?
Answer: Optic nerve head (optic disc)
The optic disc is devoid of photoreceptors where retinal ganglion cell axons exit the eye as the optic nerve, creating an absolute scotoma known as the physiologic blind spot.
Which structure forms the blood-aqueous barrier on the anterior surface of the iris?
Answer: Iris vascular endothelium with tight junctions
The anterior blood-aqueous barrier is formed by tight junctions between the endothelial cells of iris blood vessels, preventing large molecules from leaking into the aqueous humor.