COA Ocular Anatomy and Physiology 1 — Questions and Answers
Question 1: The avascular cornea receives oxygen primarily from which sources?
- The ophthalmic artery
- Tear film and aqueous humor (Correct answer)
- Vitreous humor
- Conjunctival vessels
Correct answer: Tear film and aqueous humor
The cornea gets oxygen anteriorly from the tear film and posteriorly from the aqueous humor due to its avascularity.
Question 2: Which layer of the cornea has the greatest capacity for regeneration after injury?
- Bowman's layer
- Stroma
- Descemet's membrane
- Epithelium (Correct answer)
Correct answer: Epithelium
The corneal epithelium regenerates completely within 24–72 hours because of its rapid mitotic activity.
Question 3: Aqueous humor is produced by which ocular structure?
- Trabecular meshwork
- Ciliary body (Correct answer)
- Iris
- Choroid
Correct answer: Ciliary body
The ciliary body produces aqueous humor through active secretion and passive ultrafiltration from ciliary processes.
Question 4: The macula lutea is characterized by which feature?
- Absence of all photoreceptors
- High concentration of rod cells
- High concentration of cones and the fovea centralis (Correct answer)
- Location in the nasal retina
Correct answer: High concentration of cones and the fovea centralis
The macula contains the highest cone density and the fovea centralis, providing the sharpest central vision.
Question 5: The physiologic blind spot corresponds to which ocular structure?
- The fovea centralis
- The macula lutea
- The optic disc where no photoreceptors exist (Correct answer)
- The ora serrata
Correct answer: The optic disc where no photoreceptors exist
The optic disc contains no photoreceptors because retinal nerve fibers exit here, creating a scotoma about 15 degrees temporal to fixation.
Question 6: Which cranial nerve controls the majority of extraocular muscles?
- CN IV (trochlear)
- CN VI (abducens)
- CN III (oculomotor) (Correct answer)
- CN V (trigeminal)
Correct answer: CN III (oculomotor)
CN III controls the superior rectus, inferior rectus, medial rectus, inferior oblique, and levator palpebrae superioris.
COA Ocular Anatomy and Physiology 1
The avascular cornea receives oxygen primarily from which sources?