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)"

Retinal ischemia

Retinal ischemia is an important possible aftereffect of a central retinal vein occlusion (CRVO). “Ischemia” is a term used to describe a tissue whose blood supply has been reduced to an insufficient level. Lack of oxygen in the retinal tissue may lead to retinal cell death or cell dysfunction, and thereby, result in reduced vision.