NBEO Ocular Anatomy & Physiology

Question 1

What is the function of the crystalline lens in the eye?

Accepted Answer

To change shape (accommodate) to focus light from objects at varying distances onto the retina

Answer

The crystalline lens changes shape through ciliary muscle contraction, increasing its curvature for near focus and flattening for distance focus, a process called accommodation.

Question 2

What are the three layers of the eye?

Accepted Answer

Fibrous (sclera/cornea), vascular (uvea: iris/ciliary body/choroid), and neural (retina)

Answer

The eye has three concentric layers: the outer fibrous tunic (sclera and cornea), the middle vascular tunic (uvea: iris, ciliary body, choroid), and the inner neural tunic (retina).

Question 3

What is the macula and why is it clinically significant?

Accepted Answer

The central area of the retina responsible for high-acuity color vision; its degeneration is the leading cause of central vision loss in older adults

Answer

The macula contains the highest concentration of cone photoreceptors, especially at the fovea, providing central vision for reading and facial recognition. Age-related macular degeneration (AMD) damages this critical area.

Question 4

What is intraocular pressure (IOP) and what maintains it?

Accepted Answer

The fluid pressure inside the eye, maintained by the balance between aqueous humor production by the ciliary body and drainage through the trabecular meshwork

Answer

IOP (normal: 10-21 mmHg) is maintained by aqueous humor produced by the ciliary body flowing through the pupil and draining through the trabecular meshwork. Elevated IOP is a major risk factor for glaucoma.

Question 5

What is the optic nerve and what condition damages it?

Accepted Answer

The nerve carrying visual information from the retina to the brain; glaucoma progressively damages it, causing irreversible vision loss

Answer

The optic nerve (cranial nerve II) contains approximately 1.2 million nerve fibers transmitting visual signals. Glaucoma damages these fibers, typically starting with peripheral vision loss that progresses centrally.

NBEO - National Board of Examiners in Optometry Practice Test

NBEO - National Board of Examiners in Optometry Practice Test

NBEO Ocular Anatomy & Physiology