Which vitamin, discovered in milk fat, is crucial for eyesight?

Vitamin A is essential for maintaining good eyesight, particularly in low-light conditions. It is a fat-soluble vitamin found in milk fat and plays a vital role in the formation of visual pigments in the retina, specifically rhodopsin, which is crucial for night vision. Deficiency in vitamin A can lead to problems such as night blindness and more severe forms of vision impairment.

In addition to its role in vision, vitamin A also supports immune function, skin health, and cellular communication. While other vitamins listed, such as vitamin D, vitamin C, and vitamin B12, have important health benefits, they do not directly relate to the maintenance of optimal eyesight in the way that vitamin A does. For example, vitamin D is important for bone health, vitamin C is known for its role in immune function and collagen synthesis, and vitamin B12 is vital for red blood cell formation and neurological function, but none of these affect eyesight as directly as vitamin A.