Beautiful eyes are one of the most attractive features of a face, and their color plays an important part. Color in eyes comes from the iris, which less behind the cornea and in from of the lens. In the centre of the iris is the pupil, an opening that admits lights to the eye. The iris is made up of collagen, a tough fibrous protein found also in tendons and the body’s connective tissues. Muscles fibres in the iris help it to expand or contract, controlling the amount of light going though the pupil.
Whether the iris is brown, blue or green depends on pigment called melanin, which determines also skin and hair colour. Somebody with a large amount of melanin will have brown or hazel eyes; a person with less melanin will have blue or light green eyes.
How much melanin you have depends on your parents. Two brown-eyed parents will usually have a brown-eyed child. Blue-eyed parents will almost always have blue-eyed offspring. When one parents have brown eyes and the other blue, the children usually brown-eyed. Brown eyes are a stronger hereditary trait, which explains why a vast majority of the wold’s people have brown eyes.
In rare cases, the eyes are neither brown, blue or green but pink. This is due to albinism, a genetic disorder that inhibits the production of melanin. A victim’s skin and hair may be snowy white, and the eyes at birth almost transparent. Later they darken a little. Victims suffer a number of eye problems, particularly squint, short-sightedness and intolerance of bright light. Fortunately, severe abilinism affects only one person in 20,000.