The eye

Basic structure of the eye.

The cornea is a transparent layer forming at the front of the eye. It has a convex shape and a high refractive index. The cornea does most of the focusing for the eye.

The iris is the coloured part of the eye. It is made up of muscles that control the size of the pupil. This controls in the intensity of light entering the eye.

The lens changes shape to focus light from objects at varying distances. The lens is connected to the ciliary muscles by the suspensory ligaments. When the ciliary muscles contract tension is released and the lens becomes fat and spherical. When the ciliary muscles relax the suspensory ligaments pull the lens, the lens become thinner and flatter.

Images are formed on the retina, the retina is covered in light-sensitive cells. These cells detect light and send signals to the brain…