SOD1 and age-related macular degeneration: Although the exact role of zinc in AMD is controversial [68], in general, this disease is associated with zinc deficiency, which deteriorates responses of RPE and photoreceptor cells to oxidative stress, since zinc contributes to the antioxidant defense by being a cofactor of superoxide dismutase (SOD) and upregulating other antioxidant proteins, including metallothioneins (for review, see [67]).