vitamins
There has been much research on the effect of vitamins on the eye. Vitamin A in particular seems to be important to the health of the rods and cones as this vitamin is key to the conversion of light images into an electrical signal that can be interpreted by our brain. One of the treatments attempted for people with retinitis pigmentosa (a derangement of the photoreceptors) is high doses of Vitamin A. Other vitamins have been studied in relation to macular degeneration. The AREDS Study found that a combination of Vitamin A (beta-carotene), C, and E (along with the minerals zinc and copper) seemed to slow the progression of vision loss in macular degeneration. See the AREDS Study and AREDS 2 Study for more information on this topic.