The definition of oxidative stress implies increased oxidant production in animal cells characterized by the release of free radicals, resulting in cellular degeneration. The imbalance between excess free radical production and the antioxidant defense causes cellular damage resulting in lipid peroxidation. Oxidative stress is involved in many ocular diseases such as age-related macular degeneration, retinopathy of prematurity, retinal light damage, and cataract. Reactive oxygen species are involved in this process. The pathogenesis of age-related macular degeneration is largely unknown. Excessive light and iron may enhance the progression of this disease. In in vitro study of the ciliary body, gamma irradiation inhibits TPR53BP2 expression associated with apoptotic cell death, and increased BCL2 is evident just after gamma irradiation. Exposure to ultraviolet light has been postulated as a cause of age-related macular degeneration (AMD), perhaps through damage to the retinal pigment epithelium. It seems logical, therefore, to replace the aging, yellowing lens with a blue light-absorbing yellow intraocular lens (IOL) in cataract surgery. The issue of whether cataract surgery is a risk factor for the development or progression of AMD remains controversial. In vivo studies suggest that lipid peroxidation decreases in the vitreous and retina after cataract surgery with or without intraocular lens implantation.