Glaucoma

Types of glaucoma

There are four main types of glaucoma: primary open angle glaucoma, primary angle closure glaucoma, secondary glaucoma, developmental glaucoma (congenital glaucoma).     

Primary open angle glaucoma - This is the most common type of glaucoma and develops very slowly 

Angle closure glaucoma - This is rare and can occur slowly (chronic) or may develop rapidly (acute) with a sudden, painful build-up of pressure in the eye

Secondary glaucoma -This occurs as a result of an eye injury or another eye condition, such as uveitis (inflammation of the middle layer of the eye)

Developmental glaucoma (congenital glaucoma) -This is rare but can be serious. It is usually present at birth or develops shortly after birth. It is caused by an abnormality of the eye.

In England, about 480,000 people have chronic open-angle glaucoma. Among white Europeans, about 1 in 50 people over 40 years of age and 1 in 10 people over 75 years of age have chronic open-angle glaucoma.

You are also at increased risk of developing open-angle glaucoma if you are of black-African or black-Caribbean origin.

The other types of glaucoma, such as acute angle-closure glaucoma, are much less common. However, people of Asian origin are more at risk of getting this type of glaucoma compared with those from other ethnic groups.

What are the symptoms of glaucoma?

Glaucoma does not usually cause any symptoms to begin with.

It tends to develop slowly over many years and affects the edges of your vision (peripheral vision) first.

For this reason, many people do not realise they have glaucoma, and it's often only picked up during a routine eye test.

If you do notice any symptoms, they might include blurred vision, or seeing rainbow-coloured circles around bright lights.

Both eyes are usually affected, although it may be worse in one eye.

Very occasionally, glaucoma can develop suddenly and cause:

• intense eye pain
• nausea and vomiting
• a red eye
• a headache
• tenderness around the eyes
• seeing rings around lights
• blurred vision

What causes glaucoma?

Glaucoma can occur for a number of reasons.

Most cases are caused by a build-up of pressure in the eye when fluid is unable to drain properly.

This increase in pressure then damages the nerve that connects the eye to the brain (optic nerve).

It's often unclear why this happens, although certain things can increase the risk, including:

• your age – glaucoma becomes more common as you get older
• your ethnicity – people of African, Caribbean or Asian origin are at a higher risk
• your family history – you're more likely to develop glaucoma if you have a parent or sibling with the condition
• other medical conditions – such as short-sightedness, long-sightedness and diabetes

It's not clear whether you can do anything to prevent glaucoma, but having regular eye tests should pick it up as early as possible.