Glaucoma is usually picked up during a routine eye test, often before it causes any noticeable symptoms. Other tests are usually needed afterwards to diagnose and monitor the condition.

It's important to have regular eye tests so problems such as glaucoma can be diagnosed and treated as early as possible. Early treatment can help stop your vision becoming severely affected.

You should have an eye test at least every 2 years. If you're at a higher risk of glaucoma – for example, if you have a close relative with it – you may be advised to have more frequent tests.

You can get an eye test at a local opticians. The tests are carried out in the opticians by an optometrist. Find an opticians near you.

Some people can receive free eye tests on the NHS. Find out if you're entitled to free NHS eye tests.

Tests to diagnose and monitor glaucoma

There are several quick and painless tests that can be carried out by an optometrist if they suspect you have glaucoma after a routine eye test.

Eye pressure test

An eye pressure test (tonometry) uses an instrument called a tonometer to measure the pressure inside your eye.

The optometrist will put a small amount of painkilling medication (anaesthetic) and dye into the front of your eye. They will then shine a light into your eye and gently touch the surface of it with the tonometer.

Some optometrists use a different instrument, which uses a puff of air and doesn't touch the eye, to check pressure.

Gonioscopy

Gonioscopy is an examination to look at the front part your eye – the fluid-filled space between the coloured part (iris) and the clear window of the front of the eye (cornea). This is where the fluid should drain out of your eye.

A gonioscopy can help to determine whether this area (the "angle") is open or closed (blocked), which can affect how fluid drains out of your eye. It will tell your optometrist what type of glaucoma you have.

Visual field test

A visual field test (sometimes called perimetry) checks for missing areas of vision.

You may be shown a sequence of light spots and asked to press a button to indicate which ones you can see. Some dots will appear at the edges of your vision (your peripheral vision), which is often the first area to be affected by glaucoma.

If you can't see the spots in the periphery, it may mean the glaucoma has damaged your vision.

Optic nerve assessment

The optic nerve, which connects your eye to your brain, can become damaged in glaucoma, so an assessment may be carried out to see if it's healthy.

For the test, eye drops will be used to enlarge your pupils. Your eyes are then examined using either:

• a slit lamp (a microscope with a bright light)
• optical coherence tomography – a type of scan where special rays of light are used to scan the back of your eye and produce an image of it

The eye drops used to widen your pupils could temporarily affect your ability to drive, so you'll need to make arrangements for getting home after your appointment.

Referral to a specialist

If glaucoma is picked up during an eye test, you should be referred to a specialist eye doctor (ophthalmologist) for further tests. They will confirm your diagnosis and find out:

• how far the condition has developed
• how much damage the glaucoma has done to your eyes
• what may have caused the glaucoma

They will then be able to advise on treatment. See treating glaucoma for more information.

In some cases, your ophthalmologist will continue to treat you. But for less serious types of glaucoma, you may be referred back to the opticians.

There are several different treatments for glaucoma, including eye drops, laser treatment and surgery. The best treatment for you will depend on your circumstances.

Treatment can't reverse any loss of vision that has already occurred, but it can help stop your vision getting any worse.

Your treatment plan

Your treatment will largely depend on which type of glaucoma you have. The most common type, primary open angle glaucoma, is usually treated with eye drops. Laser treatment or surgery may be offered if drops don't help.

Treatment for other types of glaucoma may include:

• primary angle closure glaucoma – immediate treatment in hospital with medication to reduce the pressure in the eye, followed by laser treatment
• secondary glaucoma – eye drops, laser treatment or surgery, depending on the underlying cause
• childhood glaucoma – surgery to correct the problem in the eye that led to the build-up of fluid and pressure

You'll also be advised to attend regular follow-up appointments to monitor your eyes and check that treatment is working. Most clinics have an eye clinic liaison officer who you'll be in contact with. It's important not to miss any of these appointments.

The main treatments are described below.

Eye drops

Eye drops are the main treatment for glaucoma. There are several different types that can be used, but they all work by reducing the pressure in your eyes.

They're normally used between 1 and 4 times a day. It's important to use them as directed, even if you haven't noticed any problems with your vision. Your sight is at risk if you don't stick to the recommended treatment.

You may need to try several types before you find the one that works best for you. Sometimes you may need to use more than one type at a time.

Eye drops can cause unpleasant side effects, such as eye irritation, and some aren't suitable for people with certain underlying conditions.

How to apply eye drops

To apply eye drops:

• use your finger to gently pull down your lower eyelid
• hold the bottle over your eye and allow a single drop to fall into the pocket you have created in your lower eyelid
• close your eye and keep it closed for a few minutes

If you're using different types of eye drops, allow at least 5 minutes between using the different types.

After you have put in the eye drops, gently press in the inside corner of the eye (over the eyelid) for about a minute. This reduces the drainage of the eye drop from the eye, which helps to increase its effect. It also helps to reduce any side effects.

Laser treatment

Laser treatment may be recommended if eye drops don't improve your symptoms.

This is where a high-energy beam of light is carefully aimed at part of your eye to stop fluid building up inside it.

Types of laser treatment include:

• laser trabeculoplasty – a laser is used to open up the drainage tubes within your eye, which allows more fluid to drain out and reduces the pressure inside
• cyclodiode laser treatment – a laser is used to destroy some of the eye tissue that produces the liquid, which can reduce pressure in the eye
• laser iridotomy – a laser is used to create holes in your iris to allow fluid to drain from your eye

Laser treatment is usually carried out while you're awake. Local anaesthetic drops are used to numb your eyes – you may just feel a brief twinge of pain or heat during the procedure.

You may still need to use eye drops after having laser treatment.

Surgery

Surgery may be recommended in rare cases where treatment with eye drops or laser haven't been effective.

The most common type of surgery for glaucoma is called trabeculectomy. It involves removing part of the eye-drainage tubes to allow fluid to drain more easily.

Glaucoma surgery may be carried out under local anaesthetic (while you're awake) or general anaesthetic (while you're asleep).

Most people won't need to take eye drops any more after trabeculectomy, and you shouldn't be in a lot of pain after surgery.

Your doctor should discuss which type of surgery they recommend, as well as any risks and benefits, before you decide whether to go ahead.

Other types of glaucoma surgery include:

• trabeculotomy – similar to a trabeculectomy, but an electric current is used to remove a small part of the eye-drainage tubes
• viscocanalostomy – part of the white outer covering of the eyeball (the sclera) is removed so fluid can drain from your eye more easily
• deep sclerectomy – the drainage tubes in your eye are widened, sometimes by implanting a tiny device inside them
• trabecular stent bypass – a tiny tube is placed into your eye to increase the drainage of fluid

After surgery, your eye might water and be red, and your vision may be slightly blurred for up to 6 weeks but should return to normal.

The hospital will give you advice about which activities you can do while you recover. Most people are advised to keep their eye dry, and avoid driving, reading and heavy lifting for at least a week.