It's usually caused by fluid building up in the front part of the eye, which increases pressure inside the eye.

Glaucoma can lead to loss of vision if it's not diagnosed and treated early.

It can affect people of all ages, but is most common in adults in their 70s and 80s.

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 1 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

In this instance you must seek Urgent attention from an eye specialist.