What is glaucoma?

Glaucoma is the name for a group of eye conditions in which the optic nerve is damaged at the point at which it leaves the eye. This nerve carries information from the light sensitive layer in your eye, the retina, to the brain where it is received as a picture.

Your eye needs a certain amount of pressure to keep the eyeball in shape so that it can work properly. In some people, the damage is cause by raised eye pressure. Others may have an eye pressure within normal limits but damage occurs because there is a weakness in the optic nerve. In most cases both factors are involved but to a varying extent.

Eye pressure is largely independent of blood pressure.

There are three main types of glaucoma. The most common is chronic glaucoma (chronic = slow). The eye pressure rises very slowly and there is no pain to show there is a problem, but the field of vision gradually becomes impaired. Acute glaucoma (acute = sudden) is much less common. This can be quite painful and will cause permanent damage to your sight if not treated promptly. When a rise in eye pressure is caused by another eye condition this is called secondary glaucoma. In the UK some form of glaucoma affects about 2 in 100 people over the age of 40.