The cause of night blindness may be a vitamin A deficiency, because dark adaptation is primarily a function of the optic rod cells in the retina, which require vitamin A for their anabolism. However, it is not necessarily a single factor that causes night blindness. It can be caused by lesions in the retina of the eye, such as retinitis pigmentosa, highly myopic fundus changes, severe glaucoma, drug toxicity or congenital anisometropia. If a patient notices a significant loss of vision and weakened dark adaptation at night or in a dark environment, the possibility of night blindness is considered and requires a detailed examination at a hospital ophthalmology clinic to analyze the cause. If it is indeed caused by vitamin A deficiency, vitamin A supplementation can be considered.