Vitamin A
Explanation
Nyctalopia, or night blindness, is a visual impairment characterized by the inability to see clearly in dim light or at night. While it can be congenital, acquired night blindness is most commonly associated with a specific nutritional deficiency affecting the photoreceptor cells in the retina.
Analysis of Options:
- Vitamin A (Correct): Vitamin A (Retinol) is essential for the synthesis of rhodopsin (visual purple), a light-sensitive pigment found in the rod cells of the retina. Rod cells are responsible for vision in low-light conditions. A deficiency in Vitamin A prevents the regeneration of rhodopsin, leading to night blindness. Prolonged deficiency can lead to Xerophthalmia (dryness of the eye) and permanent blindness.
- Vitamin C: Deficiency of Vitamin C (Ascorbic acid) primarily causes Scurvy, characterized by bleeding gums, skin spots, and poor wound healing. It is not linked to night blindness.
- Vitamin D: Deficiency of Vitamin D (Calciferol) affects calcium absorption, leading to Rickets in children and Osteomalacia in adults (weakening of bones).
- Vitamin B: The Vitamin B complex includes several vitamins. For instance, deficiency of Vitamin B1 (Thiamine) causes Beriberi, and Vitamin B3 (Niacin) deficiency causes Pellagra. None are the primary cause of night blindness.
Key Takeaway:
Vitamin A is critical for the formation of rhodopsin in rod cells, which enables scotopic (low-light) vision; its deficiency is the primary nutritional cause of Nyctalopia.