The eye

The eye is, simply said, a ball, with some coats covering the outside.

At the front of the eye is the cornea, which is transparent like glass, and causes the most of the focussing (breaking, in order to get it in focus on the retina) of the light. In the anterior chamber , behind the cornea, is a fluid that is being produced all the time. This causes a pressure in the eye, “squeezing” out some of this fluid (the same amount that is being made, so the eye has a more or less constant pressure).

The pressure of the eye is often increased in the condition of glaucoma. The iris is the coloured part of the eye, and contains muscles that allow it to open and narrow the pupil. The lens is important in keeping the focus of an image on the retina. As we get older, the lens hardens and it gets more and more difficult to focus on things near. Then we need reading glasses. A clouding of the lens is called a cataract. The centre of the eye with a transparent substance the vitreous (jelly of the eye). This has an important role in keeping the eye in its ball-like shape. It shrivels up with age, and may come off the retina to which it is attached, causing floaters or even retinal detachments.