Glaucoma causes fluid in the eye to build up, which ratchets up the pressure inside. The high pressure damages the optic nerve which sends signals from the eye to the brain to enable the person to see. The damage is irreversible and can lead to blindness in severe cases.
The disease comes in several forms. The majority of patients develop a form called primary open angle glaucoma. It progresses slowly and painlessly and destroys peripheral vision before central vision, so patients often do not notice that their vision is deteriorating.
Another form called acute angle closure glaucoma, which tends to hit older Chinese, occurs suddenly. Pressure in the eye rises rapidly, causing pain and redness in the eye, blurred vision, headache and nausea.
Less than five per cent of the population suffers from glaucoma, which is linked to ageing. The risk of getting it is about three per cent for those aged 40 and above, but about nine per cent for those aged 70 and above. The risk also rises when there is a family history of glaucoma, extreme short-sightedness or chronic diseases like diabetes and high blood pressure. Eye inflammation, advanced cataracts, tumours, injuries and surgery can cause glaucoma.
Most of the risk factors cannot be prevented. Screening to detect the
disease early is important, as treatment can arrest its progression in most cases. The disease is usually treated with eye drops to lower the pressure. Laser treatment or surgery are used usually at a later stage. However, some patients still end up losing their sight for good. In a 2003 study on 186 patients in the United States, nine per cent were found to be blind in both eyes after 15 years, despite treatment.
Top 5 causes of blindness:
2. Undercorrected refractive errors
4. Macular degeneration
5. Diabetic Retinopathy