SOD1 and cataract: Melatonin has also been shown to have an antioxidant effect against radiation-induced cataracts by increasing the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) while decreasing the levels of lipid peroxidation (as assessed using malondialdehyde [MDA]), thereby reducing oxidative stress caused by radiation and protecting the lens from radiation-induced damage [34].