COST COST Ocular Anatomy and Physiology 2

Question 1

What is the approximate axial length of a typical emmetropic adult human eye?

Accepted Answer

24 mm

Answer

The average emmetropic adult eye has an axial length of approximately 24 mm, which is a key biometric measurement used in IOL power calculations.

Question 2

The vitreous humor occupies approximately what percentage of the total volume of the eye?

Accepted Answer

60%

Answer

The vitreous humor fills the posterior segment and accounts for roughly 60% of the eye's total volume, providing structural support and a clear optical medium.

Question 3

Which cells of the retina are primarily responsible for phototransduction in low-light (scotopic) conditions?

Accepted Answer

Rod cells

Answer

Rod photoreceptors contain rhodopsin and are exquisitely sensitive to dim light, making them the primary mediators of scotopic (night) vision.

Question 4

The lens of the eye is held in place by which fibrous structure?

Accepted Answer

Zonules of Zinn (zonular fibers)

Answer

The zonules of Zinn (suspensory ligament of the lens) are fibrillin-rich fibers that connect the ciliary body to the lens equator, holding the lens in position.

Question 5

Which layer of the retina lies immediately adjacent to the retinal pigment epithelium (RPE)?

Accepted Answer

Photoreceptor outer segments

Answer

The outer segments of photoreceptors (rods and cones) are in direct contact with the microvilli of the RPE, which phagocytoses shed outer segment discs.

COST - Certified Ophthalmic Surgical Technologist Practice Test

COST - Certified Ophthalmic Surgical Technologist Practice Test

COST COST Ocular Anatomy and Physiology 2