Deficiency of Vitamin A is the main cause of night blindness. This condition, medically known as nyctalopia, occurs due to the impaired function of the retina, affecting the ability to see in low light conditions. Vitamin A plays a crucial role in maintaining healthy vision, particularly in the adaptation of the eyes to darkness. Without sufficient Vitamin A, the production of rhodopsin, a pigment necessary for low-light vision, is compromised, leading to night blindness. Thus, ensuring an adequate intake of Vitamin A-rich foods such as carrots, spinach, sweet potatoes, and liver can help prevent this deficiency and maintain optimal eye health.