USA Biology Olympiad (USABO) Practice Exam

What common condition does "night blindness" indicate, particularly in children?

1. Vitamin B12 deficiency

2. Vitamin A deficiency

3. Vitamin C deficiency

4. Zinc deficiency

The correct answer is: Vitamin A deficiency

Night blindness is a condition that indicates difficulties with vision in low light or darkness, and it is particularly associated with vitamin A deficiency. Vitamin A is crucial for the production of rhodopsin, a pigment in the retina that enables the eyes to adapt to dim light. If the body lacks adequate vitamin A, the synthesis of rhodopsin is impaired, leading to the inability to see well in low-light conditions, which manifests as night blindness. In children, this deficiency can arise due to inadequate dietary intake, especially in regions where food sources rich in vitamin A, like leafy greens, carrots, and liver, are not sufficient. Early intervention with vitamin A supplementation or dietary changes can help restore vision and prevent more severe health issues related to vitamin A deficiency, such as xerophthalmia and increased risk of infections. The significance of recognizing night blindness as a sign of potential vitamin A deficiency is critical in public health, particularly in areas where such deficiencies are prevalent.