**Question:** Keratomalacia (REPEATED question)

**Core Concept:** Keratomalacia is a severe form of vitamin A deficiency, which affects the cornea, leading to impaired vision and potentially blindness. Vitamin A is essential for maintaining corneal integrity, regulating cell proliferation, and preserving the corneal epithelium.

**Why the Correct Answer is Right:** Vitamin A plays a vital role in maintaining corneal integrity, and its deficiency results in keratomalacia. The primary target of vitamin A is the corneal epithelium, which is responsible for regenerating the corneal surface and preventing corneal ulceration. In the absence of sufficient vitamin A, the corneal epithelium fails to regenerate, leading to the formation of ulcers and subsequent impaired vision or blindness.

**Why Each Wrong Option is Incorrect:**

A. Option A: Vitamin A deficiency is not solely responsible for keratomalacia. Other factors like malnutrition, concurrent infections, or autoimmune disorders can also contribute to the condition.

B. Option B: Vitamin A deficiency does not exclusively affect the cornea. Other vitamin A-dependent processes, such as visual acuity and immune system function, can also be impaired.

C. Option C: Although vitamin A deficiency is a risk factor for keratomalacia, it is not the sole cause. Other factors, like severe malnutrition, can exacerbate the condition.

D. Option D: Vitamin A deficiency is not only responsible for keratomalacia. Other factors like environmental factors, such as inadequate sunlight exposure, can contribute to vitamin A deficiency and subsequent keratomalacic symptoms.

**Clinical Pearl:**

Keratomalacia is a severe form of vitamin A deficiency that primarily affects the cornea, leading to impaired vision and potentially blindness. It is essential to identify and address the underlying causes of vitamin A deficiency (malnutrition, concurrent infections, autoimmune disorders, sunlight exposure, etc.) to prevent and manage this condition.

**Correct Answer:** D (Vitamin A deficiency is one of the contributing factors to keratomalacia)