What causes eyes to change color?
Eye color change Often, paler newborns have blue eyes, which change to green, hazel, light brown or dark brown, as they grow older. This is probably the origin of the idiom “being blue-eyed” (i.e. naïve; gullible). It is thought that exposure to light after birth triggers the production of melanin in the iris of the eye. By three years of age, the eyes produce and store enough melanin to indicate their natural shade. While changes in eye color of infants are more common, even in adults, eye color changes are seen, most often as a result of exposure to the sun. Sunlight triggers melanin production in the eye, as it does to the skin. Eyedrops containing a prostaglandin analogue (such as latanoprost) may result in a permanently darkened iris; these eyedrops are commonly used to treat open-angle glaucoma.
