American Board of Ophthalmology (ABO) Practice Exam 2025 - Free Ophthalmology Practice Questions and Study Guide.

Vitamin A plays a crucial role in maintaining proper vision, particularly in low-light conditions. A deficiency in Vitamin A can lead to night blindness, also known as nyctalopia. This occurs because Vitamin A is a vital component of rhodopsin, a light-sensitive pigment found in the rod cells of the retina. Rod cells are primarily responsible for vision in dim light. When there is an insufficient amount of Vitamin A, the synthesis of rhodopsin is impaired, leading to difficulties seeing in the dark or poor vision at night.

In contrast, while color blindness, cataracts, and glaucoma are significant visual impairments, they are not directly associated with Vitamin A deficiency. Color blindness is related to genetic factors affecting the cones responsible for color discrimination. Cataracts involve the clouding of the lens of the eye due to aging, diabetes, or other risk factors, but not Vitamin A deficiency. Glaucoma is a group of eye conditions that damage the optic nerve, often related to increased intraocular pressure, rather than a deficiency in vitamins.

Thus, Vitamin A deficiency specifically leads to night blindness, highlighting its essential role in the visual cycle and the health of the retina.