Glaucoma
Glaucoma is the name given to a group of eye conditions in which the optic nerve is damaged where it leaves the eye. Although any vision which has been lost to glaucoma cannot be recovered, with early diagnosis, careful monitoring and regular use of the treatments, further damage to vision can be prevented and most patients retain useful sight for life. While there are usually no warning signs, regular eye tests will help detect the onset of the disease.
Glaucoma is one of the world's leading causes of blindness. In the UK, about two per cent of the population over 40 have the condition.
How glaucoma affects vision
Glaucoma involves loss of vision due to damage of the optic nerve. The optic nerve carries sight images to the brain and any damage to the nerve results in damage to sight.
For the eye to work properly a certain level of pressure is needed for the eye to keep its shape but if the eye pressure gets too high, it squeezes the optic nerve and kills some of the nerve fibres, which leads to sight loss. The first areas to be affected are the off-centre parts of the vision. If the glaucoma is left untreated, the damage can progress to tunnel vision and eventual loss of central vision, although blindness is rare.
Usually, but not always, the damage occurs because pressure within the eye increases and presses on the nerve, which damages it.