Eye injuries

The structure of the face is designed to protect the eyes from injury. Each eyeball is set into a protective socket of bone (known as an orbit), and the eyelids can close very quickly to form a protective barrier.

However, eye injuries can still occur, usually as a result of a scratch or graze (abrasion) caused by something in the eye such as grit or a contact lens.

These injuries cause damage to the cornea, which is the transparent outer layer of the eye. The cornea covers and protects the coloured part of the eye (iris), and lets light into the hole in the centre (pupil).

Structure of the cornea

Although it appears to be very thin, the cornea is made up of five layers. From the outside of the cornea to the inside, the layers are:

• The epithelium, a protective outer membrane that keeps the eye moist.
• The Bowman's membrane, a thin layer of transparent tissue underneath the epithelium.
• The stroma, a layer of connective tissue which supports the cornea.
• The Descemet's membrane, a flexible liquid-like layer which covers the inner surface of the cornea.
• The endothelium, a single layer of thin flat cells which form the inner surface of the cornea.