Glaucoma types and overview
Glaucoma is an eye condition affecting a person's vision, usually linked to a build-up of pressure inside the eye.
Glaucoma is estimated to affect over 500,000 people in England and Wales. It causes around 1 in 10 cases of vision impairment.
Extra pressure in the eye can damage the optic nerve and nerve fibres from the retina at the back of the eye causing loss of vision.
Glaucoma can be slow to develop and may cause no symptoms until vision starts to get worse.
What causes glaucoma?
Drainage tubes are supposed to stop any pressure building up in the clear fluid in the eye (aqueous humour), but if the tubes get blocked this natural pressure valve doesn't work.
One eye or both eyes may be affected.
Pressure in the eye - called intraocular pressure - should be tested during routine eye tests to check for early signs of glaucoma.
Who has a greater chance of developing glaucoma?
Although it isn't clear why some people get glaucoma and others don't, some things are known to increase the chances of it developing, including:
- Age - glaucoma is more likely as we age
- Ethnic origin - people with African or African-Caribbean backgrounds are at a greater risk
- Being short-sighted ( myopia)
- Having ocular hypertension - increased pressure in the eye
- Having a close family member with glaucoma, such as a parent, brother or sister
- Having medical conditions, including diabetes
- Having a condition causing fibres to block the eye ducts.
What are the main types of glaucoma?
The main types of glaucoma and their symptoms are:
- Chronic open-angle glaucoma - the most common type, and slow to develop with few symptoms until peripheral vision starts to become lost.
- Primary angle-closure glaucoma - rare and can come on suddenly causing eye pain, redness, eye tenderness, headaches, seeing halos around things, misty vision and vision loss.
- Secondary glaucoma - after an eye injury or infection causing cloudy vision and halos.
- Developmental glaucoma or congenital glaucoma - present from birth and rare, with symptoms including bigger eyes, light sensitivity, cloudy looking eyes, eyes watering, jerky eye movements and squinting.
See an optometrist at your local optician’s for an eye check if you have symptoms that might indicate glaucoma, even if it is between routine tests every 2 years. You may have to pay for this depending on where you live in the UK and your circumstances.
How is glaucoma diagnosed?
The optometrist may put drops in the eye to dilate the pupils and to numb them before the tests. You shouldn't drive for some time after having pupils dilated.
Using various instruments, they will check:
- Eye pressure (tonometry).
- Central corneal thickness, which may affect pressure in the eye.
- The front part of the eye's outer edge where fluid drainage should occur (gonioscopy),
- Visual field test, also called a perimetry test, to check for missing areas of vision by looking at patterns of spots. If you can't see them all, some peripheral vision may already have been lost.
- Optic nerve assessment, using a slit lamp.
If glaucoma is suspected, the optometrist will usually let your GP know and will usually make a referral to a specialist ophthalmologist for further assessment and treatment.