The vitamin crucial for maintaining healthy eyesight is vitamin A. This fat-soluble vitamin is essential for maintaining proper vision, particularly in low-light conditions, as it is a key component of rhodopsin, a protein in the eyes that enables night vision. Vitamin A also plays a role in the overall health of the retina and helps prevent age-related eye diseases, such as macular degeneration and cataracts. Sources of vitamin A include foods like carrots, sweet potatoes, spinach, and liver. Adequate intake of this vitamin is vital for both vision and immune function.