Eyes

"The eye is the organ of sight (vision) in humans and animals. The eye works by transforming light waves into visual images. Eighty percent of all information received by the human brain comes from the eyes. Eye color is created by the amount and type of pigment in the iris. Multiple genes inherited from each parent determine a person’s eye color. The eye is a slightly asymmetrical globe, about an inch in diameter. The front part of the eye (the part you see in the mirror) includes:
• The iris (the pigmented part)
• The cornea (a clear dome over the iris)
• The pupil (the black circular opening in the iris that lets light in)
• The sclera (the white part)
• The conjunctiva (an invisible, clear layer of tissue covering the front of the eye, except the cornea)"

Degenerative diseases eyes

A degenerative eye disease is a collective term for a disease that affects the various parts of the eye, including the retina, cornea, iris and macula. The common prognosis is a progressive loss of central vision. The diseases of the eye can be classified as inherited, associated with another medical condition, caused by a virus and cancer. Common and disease-specific symptoms are associated with each eye malady.