COT Ocular Anatomy and Physiology 4 — Questions and Answers
Question 1: Which layer of the cornea is responsible for approximately 90% of its thickness?
- Epithelium
- Bowman's layer
- Stroma (Correct answer)
- Descemet's membrane
Correct answer: Stroma
The stroma constitutes about 90% of the corneal thickness and is composed of regularly arranged collagen lamellae.
Question 2: The canal of Schlemm is primarily involved in:
- Lens accommodation
- Aqueous humor outflow (Correct answer)
- Vitreous humor production
- Retinal blood supply
Correct answer: Aqueous humor outflow
The canal of Schlemm collects aqueous humor from the trabecular meshwork and drains it into the episcleral venous system.
Question 3: Which photoreceptors are most densely concentrated in the fovea centralis?
- Rods
- Cones (Correct answer)
- Ganglion cells
- Bipolar cells
Correct answer: Cones
The fovea centralis contains only cones at its center, providing the highest visual acuity and color discrimination.
Question 4: The ciliary body performs which TWO primary functions?
- Produces aqueous humor and controls accommodation (Correct answer)
- Drains aqueous humor and produces tears
- Controls pupil size and produces vitreous
- Absorbs light and maintains IOP
Correct answer: Produces aqueous humor and controls accommodation
The ciliary body secretes aqueous humor via the ciliary epithelium and controls lens shape for accommodation through the ciliary muscle.
Question 5: The optic nerve head (optic disc) lacks photoreceptors, creating what clinical finding?
- Central scotoma
- Physiologic blind spot (Correct answer)
- Ring scotoma
- Arcuate scotoma
Correct answer: Physiologic blind spot
The optic disc has no photoreceptors, creating a natural blind spot approximately 15 degrees temporal to fixation.
Question 6: Bruch's membrane separates the retinal pigment epithelium from which structure?
- Vitreous body
- Retinal nerve fiber layer
- Choriocapillaris (Correct answer)
- Ora serrata
Correct answer: Choriocapillaris
Bruch's membrane is a pentalaminar structure between the RPE and the choriocapillaris, important in macular disease pathogenesis.
Question 7: The posterior chamber of the eye is bounded anteriorly by the iris and posteriorly by the:
- Cornea
- Vitreous face and lens (Correct answer)
- Trabecular meshwork
- Retina
Correct answer: Vitreous face and lens
The posterior chamber lies between the posterior iris surface anteriorly and the anterior vitreous face and crystalline lens posteriorly.
COT Ocular Anatomy and Physiology 4
Which layer of the cornea is responsible for approximately 90% of its thickness?