Three common types of eye diseases in humans are conjunctivitis, cataracts and glaucoma. Conjuctivitis, or pink eye, occurs due to a viral or bacterial infection in the eye, causing inflammation and redness on the whites of the eyes as well as the inner part of the eyelid.
A cataract is a degenerative condition in which the lens of the eye hardens and becomes cloudy, making it difficult to properly focus light. Glaucoma is a build-up of fluid that puts an unsafe pressure on the eye, which causes damage to the optic nerve. Each of these conditions require regular visits to an eye doctor for diagnosis and treatment.