Impaired ability to adapt to darkness. Usual cause is a lack of rhodopsin, or visual purple in the eye.
Diet:
Eat foods rich in vitamin A such as spinach, collard greens, carrots, cantaloupe, mustard greens, and oysters, lean beef, and black-eyed beans, all good sources of zinc.
Nutrients:
Vitamin A, zinc, grape seed extract.
Herbs:
Bilberry.