**Core Concept:** Glaucoma is a group of diseases that damage the optic nerve, often resulting in progressive vision loss. The visual field is the area of the retina that senses light and converts it into electrical signals that travel to the brain for interpretation. In glaucoma, the damage to the optic nerve leads to a characteristic pattern of visual field loss.

**Why the Correct Answer is Right:** In glaucoma, the optic nerve fibers that are responsible for transmitting visual information from the retina to the brain degenerate, resulting in a characteristic pattern of visual field loss. In this case, the correct answer is **C.** The peripheral visual field is the last area to be affected in glaucoma. The peripheral field loss occurs because the optic nerve fibers are more vulnerable to the effects of elevated intraocular pressure (IOP) due to their smaller size and less efficient collateral circulation.

**Why Each Wrong Option is Incorrect:**

A. **Last visual field to be affected:** The correct answer explains that the peripheral visual field is affected first, not the central field. Central vision loss would be more severe and progressive, which is not the pattern observed in glaucoma.

B. **Largest visual field:** Glaucoma affects the peripheral visual field first, not the largest field.

D. **First visual field to be affected:** This is the opposite of the correct answer, as the peripheral field is affected first in glaucoma.

**Clinical Pearl:** Glaucoma is a crucial topic for medical students and residents to understand due to its prevalence and impact on patient care. Early diagnosis and treatment can help preserve visual function and prevent progression of the disease. Glaucoma affects patients of all ages, races, and eye conditions, and can lead to irreversible blindness if left untreated.

**Correct Answer:** C. Last visual field to be affected in glaucoma.