Cataracts are a gradual clouding of the lens (a part of the eye which transmits and focuses light), which is typically clear. This scatters the light and prevents the lens from sending a clear image to the retina, a layer of cells at the back of the eye that converts the light into signals the brain is able to process. Most people will experience cataracts at some point in their life, typically beginning in their sixties; untreated cataracts are a significant cause of blindness worldwide. Symptoms may progress for years before being observed—as proteins clump in the lens and become more opaque, preventing light from focusing clearly on the macula (focal point) in the centerof the retina, changes in vision like blurriness, halos around bright objects, and faded colors will become noticeable. Cataracts are not visible to the naked eye, nor do they cause irritation or discomfort of the eye, and are diagnosed by an ophthalmologist on exam.