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Glaucoma is an eye condition that causes damage to the optic nerve at the back of your eye. The optic nerve connects your eye to your brain, so untreated glaucoma can cause blindness.

The eye has a pump that produces a small amount of fluid to keep enough pressure in the eyeball, so it doesn’t collapse. If this fluid drains properly, the eye pressure (also called intraocular pressure) is low, but if it doesn't drain easily, the eye pressure rises. If the pressure gets too high, the optic nerve can be permanently damaged.

It's also possible for your optic nerve to be damaged even if your eye pressure is normal.

Glaucoma is often detected during routine eye examinations. If it's caught early, it can be treated so you do not lose your sight.

Glaucoma is more common as you get older, with about one in 10 people over 70 years old having it.

You're also at a higher risk of glaucoma if you:

Types of glaucoma

There are many different types of glaucoma, which can cause different symptoms and need different treatments.

Most people have open-angle glaucoma. In this type of glaucoma, fluid cannot flow out of your eye properly, and the pressure gets too high. This video shows how it happens.

Some people get acute angle-closure glaucoma, but this is less common. In this type of glaucoma, the channels draining fluid from your eye become completely and suddenly blocked.

Other types of glaucoma include low-tension, angle-recession, steroid-induced, pigmentary and neovascular glaucoma. Occasionally, babies are born with glaucoma.

Symptoms of glaucoma

Most people with open-angle glaucoma have no symptoms until the disease is severe.

The first signs you may notice are usually blind spots at the sides of your vision (peripheral vision loss) and in some cases reduced central vision.

In cases of acute angle-closure glaucoma and some other causes of glaucoma, you may suddenly develop the following symptoms:


Acute angle-closure glaucoma is a medical emergency and must be treated immediately.

Diagnosing glaucoma

Glaucoma is diagnosed by testing your vision, including peripheral vision (visual field tests), looking through your pupil directly at the optic nerve and by measuring your eye's pressure (intraocular pressure).

A good first step is to see an optometrist for these tests. You can also see your general practice team, but they may advise you to see an optometrist who can do more detailed tests. If your optometrist or general practice team think you may have glaucoma, they will refer you to an ophthalmologist (eye doctor) who can confirm the diagnosis and start treatment.

Treating glaucoma

There is no cure for glaucoma, but there are treatments that can control it and prevent further damage. Unfortunately, any existing damage to the optic nerve is permanent. If you do not treat glaucoma, the damage will get worse, and you can lose your sight.

Treatment for glaucoma aims to lower the pressure inside your eye to prevent any further damage to your optic nerve. It can do this in two ways:

You'll need to continue treating your glaucoma for the rest of your life.

The main treatment is with medicated eye drops and sometimes tablets. You might also have laser treatment, surgery or a combination of these methods.

Glaucoma medications come in different strengths and combinations. Eye doctors (ophthalmologists) try to use the smallest amount of medication with the fewest side effects. You might need several medications that complement each other. You'll need to use medications every day to control the pressure in your eye.

Like all medicines, the eye drops can have side effects, although many people do not get them. Mild eye irritation or pain is common. But if your eyes are always sore, your vision is blurred or you develop a red rash around your eyes, you should speak to your doctor as soon as possible.

Reducing your risk of glaucoma

The best way to prevent glaucoma damaging your sight is to have regular eye examinations. How often you should have an eye examination depends on your circumstances:

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Written by Canterbury optometrists. Adapted by HealthInfo clinical advisers. Last reviewed March 2023.


Page reference: 114674

Review key: HIGLC-114674