Glaucoma is a common eye condition where the optic nerve, which connects the eye to the brain, becomes damaged.

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

Your eye contains a clear, watery liquid that feeds the inside of the eye. Liquid is constantly being drained out of the eye and new liquid is made to replace this. If the liquid cannot drain out quickly enough, the pressure inside the eye builds up. This medicine works by increasing the amount of liquid that is drained. This reduces the pressure inside the eye. If the high pressure is not reduced, it could lead to a disease called glaucoma and eventually damage your sight.

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.

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

Visit an opticians or a GP if you have any concerns about your vision.

If you have glaucoma, early diagnosis and treatment can help stop your vision getting worse.

Without treatment, glaucoma can eventually lead to blindness.

If you develop symptoms of glaucoma suddenly, go to your nearest eye casualty unit or A&E as soon as possible.

This is a medical emergency that may require immediate treatment.

There are several different types of glaucoma.

The most common is called primary open angle glaucoma. This tends to develop slowly over many years.

It’s caused by the drainage channels in the eye becoming gradually clogged over time.

Other types of glaucoma include:

• acute angle closure glaucoma – an uncommon type caused by the drainage in the eye becoming suddenly blocked, which can raise the pressure inside the eye very quickly
• secondary glaucoma – caused by an underlying eye condition, such as inflammation of the eye (uveitis)
• childhood glaucoma (congenital glaucoma) – a rare type that occurs in very young children, caused by an abnormality of the eye

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.

The treatment recommended for you will depend on the type of glaucoma you have, but the options are:

• eyedrops – to reduce the pressure in your eyes
• laser treatment – to open up the blocked drainage tubes or reduce the production of fluid in your eyes
• surgery – to improve the drainage of fluid

You’ll also probably need regular appointments to monitor your condition and check the treatment is working.