Night blindness means difficulty seeing in low light or darkness.

Disorder of rods cells causes night blindness. Vitamin A plays a crucial role in the formation of rhodopsin, a photopigment found in the rod cells of the retina that is essential for vision in low-light conditions. Moreover, vitamin A plays a role in transforming  nerve impulses into images in the retina.

Hence, deficiency of vitamin A in the body is one of the main causes of night blindness.