Glaucoma is damage to your eye’s optic nerve. If left untreated it can lead to sight loss.

By Wallace Health I Medically reviewed by Adrian Roberts.
Page last reviewed: October 2018 I Next review due: October 2023

What is glaucoma?

Glaucoma refers to a group of eye diseases that are usually caused by a build-up of pressure in the fluid inside your eye. This can damage the optic nerve, which links your eye to your brain and enables you to see.

Glaucoma usually develops gradually, initially affecting the outer edge of your vision (tunnel vision) and later causing patchy or blurred vision. If undiagnosed or diagnosed too late, glaucoma can result in permanent blindness. However, this is less likely in the UK as many cases of glaucoma are picked up during a routine eye check.

Although it’s quite common, it mostly affects people in their 70s and 80s.

If your eyesight has been damaged by glaucoma, it can’t be repaired. However, once diagnosed, regular eye checks and eye drops to relieve the pressure of fluid in your eye should prevent further vision loss. You will usually need treatment for your glaucoma for the rest of your life. 

There are several kinds of glaucoma. The two main kinds are chronic (long-term) glaucoma and acute angle-closure glaucoma.

Chronic glaucoma, also known as primary open-angle glaucoma, is the most common. Initially symptomless, chronic glaucoma develops slowly — you may not realise you have it until you lose your vision. It is caused by the drainage channels (trabecular meshwork) between your cornea and iris (coloured part of your eye) becoming clogged over time, which increases the pressure in your eye.

Acute angle-closure glaucoma, also known as closed-angle glaucoma, is much less common than chronic glaucoma. It is caused by a rapid increase in eye pressure when the drainage channels suddenly become blocked — this usually happens because the iris bulges out, partially or completely covering the drainage channels. If you naturally have narrow drainage channels, you are at greater risk of acute angle-closure glaucoma. It's extremely painful and needs urgent medical attention to prevent permanent damage to your sight.

Angle-closure glaucoma can also occur gradually — this is called chronic angle-closure glaucoma. One in three people with chronic angle-closure glaucoma will have an attack of acute angle-closure glaucoma.

Other kinds of glaucoma are:

  • Congenital glaucoma — a rare condition affecting very young children, which is caused by an eye abnormality
  • Normal-tension glaucoma — eye pressure remains normal but your optic nerve is still damaged; the cause is unknown but may be due to a sensitive optic nerve or poor blood supply to the optic nerve eg caused by a build-up of fatty deposits in your arteries (atherosclerosis) or other conditions that affect your blood supply
  • Pigmentary glaucoma — pigment granules from your iris build up and clog the drainage channels of your eye, which causes intermittent increases in your eye pressure; certain activities can dislodge pigment granules from your iris and cause them to deposit in your drainage channels eg jogging
  • Secondary glaucoma — often caused by an eye infection, eye injury or medication

How to tell if you have glaucoma

Chronic glaucoma can take years to develop. In fact, you may not realise there’s a problem with your sight as glaucoma symptoms are difficult to spot. It may only be picked up during your routine eye test. However, you may notice your vision becoming blurry as glaucoma progresses, usually affecting your peripheral (side) vision first, as well as rainbow-coloured halos around bright lights. Chronic glaucoma usually affects both eyes, although your symptoms may be worse in one eye.

Acute angle-closure glaucoma happens without warning and can seriously damage your vision. Visit your nearest A&E department immediately if you have sudden, severe eye pain and any or all of the following:

  • A red eye
  • Are seeing haloes around lights
  • Blurred vision
  • Patchy blind spots in your central and peripheral vision, usually in both eyes
  • Tunnel vision — this usually occurs in advanced stages
  • Tenderness around the eye area

You may also have a headache and vomiting.

Talk to your doctor if you’re concerned about symptoms

You can book an appointment with a Spire private GP today.

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Diagnosis and tests for glaucoma

If you are worried about your vision, visit your optician or GP. 

If you experience symptoms of acute angle-closure glaucoma, go straight to A&E. 

Glaucoma symptoms are easy to miss, so it’s important to have a routine eye test every two years or more frequently if you are high risk eg if you have a close relative with glaucoma —  your optician will advise you on how often you should have an eye test. 

Glaucoma is usually diagnosed during a routine eye test before you have any noticeable visual symptoms. Early diagnosis is key to avoiding more serious damage to your vision. 

During your eye test, your optometrist will carry out glaucoma tests to check your vision, eye pressure and optic nerve. If glaucoma is detected, your optician will refer you to a specialist eye doctor called an ophthalmologist.

If your ophthalmologist confirms you have glaucoma, they’ll recommend treatment and regular follow-up appointments. They will also assess you to determine: 

  • How far your glaucoma has progressed
  • How much your eyes have been damaged by glaucoma
  • What may have caused your glaucoma

Eye pressure test

An eye pressure test, also known as tonometry, measures the pressure inside your eye using a device called a tonometer. Your optometrist will apply a local anaesthetic and a dye to the front of your eye. Next, they will shine a light onto your eye and gently touch its surface with the tonometer to detect your eye pressure.

Tonometry may also be performed using an air-puff tonometer — this applies a puff of air onto the front of your eye instead of touching it. 


Gonioscopy examines the front of your eye, specifically the fluid-filled space between your iris and cornea (the transparent part at the front of your eye). In healthy eyes, fluid should drain out from this space at the same rate as it is replenished. 

Gonioscopy can check if this space, which is called the angle, is open or closed (blocked). This will help your optometrist determine what type of glaucoma you have. 

Visual field test

A visual field test, also known as perimetry, checks for areas where you have lost your vision. Your optometrist may show you a sequence of light spots and ask you to press a button every time you see a light spot. Some spots will appear in your peripheral vision, which is usually the first to deteriorate in glaucoma. If you can't see the light spots in your peripheral vision, it may be because glaucoma has damaged your peripheral vision.

Optic nerve assessment

The optic nerve connects your eye to your brain and can be damaged by glaucoma. Your optometrist will check if it’s healthy by applying eye drops to enlarge your pupils and then looking through your eyes to see your optic nerve. This may be done using: 

  • A slit lamp — a microscope with a bright light
  • Optical coherence tomography — a scan that uses special light rays to create images of the back of your eye where your optic nerve is located

You will not be able to drive after having eye drops to enlarge your pupils so make sure you arrange an alternative way to get home after your optic nerve assessment. 

Causes of glaucoma

Glaucoma is usually caused by a build-up of pressure in the fluid inside your eye because the fluid can't drain properly, or in some cases because too much fluid is produced. This damages the optic nerve and causes blind spots in your vision. It isn't fully understood why increased eye pressure causes nerve damage. 

You’re more likely to develop glaucoma if:

  • A parent, brother or sister has glaucoma — glaucoma can run in families; research has identified some gene variations associated with high eye pressure and optic nerve damage
  • You have diabetes, heart disease, high blood pressure or sickle cell anaemia
  • You have raised eye pressure (ocular hypertension)
  • You’re of African, Caribbean or Asian origin
  • You’re older — glaucoma becomes more common with age 
  • You’re very short-sighted or long-sighted

Your risk of glaucoma is also higher if you have: 

  • Been taking corticosteroid medications, particularly eye drops, for a long time
  • Corneas that are thin in the centre
  • Had an eye injury or certain types of eye surgery

There isn’t clear evidence on whether there are steps you can take to prevent glaucoma. However, keeping up with your routine eye tests will mean it is detected as early as possible. 

Common treatments for glaucoma

Damage to your eye caused by glaucoma is permanent and can't be reversed. However, regular check-ups and treatment can slow or prevent further damage and vision loss, particularly if you get treatment early. 

Your ophthalmologist will recommend treatment to reduce your high eye pressure; the specific treatment will depend on the type of glaucoma you have. Primary open-angle glaucoma, which is the most common type of glaucoma, is usually treated with daily eye drops.

However, your ophthalmologist may recommend laser treatment or surgery to drain the fluid that is causing your high eye pressure.

Acute angle-closure glaucoma needs urgent treatment in hospital with medication to reduce your eye pressure. After this, you will need laser treatment. 

Congenital glaucoma is treated with surgery to correct the eye abnormality causing the high eye pressure. 

Secondary glaucoma can be treated with eye drops, laser treatment or surgery, depending on what caused it. 

Whichever type of glaucoma you have, your ophthalmologist will recommend regular follow-up appointments to monitor your eyes and the effectiveness of your treatment. It is important that you keep up with these appointments to protect your vision. Most eye clinics have a liaison officer who will contact you.

Eye drops

Eye drops that reduce your eye pressure are the most common treatment for glaucoma. There are several different types, which are usually applied one to four times a day. Even if you haven't noticed any vision problems, you should continue using your eye drops as instructed by your ophthalmologist — if not, you may put your vision at risk. 

You may need to try a few different types of eye drops to find the one that is most effective for you or you may need to use more than one type. Not all eye drops are suitable for everyone, particularly if you have other underlying medical conditions — your ophthalmologist will advise you on which are most appropriate for you. Side effects often include eye irritation. 

To apply your eye drops, make sure you:

  • Gently pull your lower eyelid down using your finger
  • Hold your eye drop bottle over your eye and let one drop fall into the pocket created by pulling down your lower eyelid
  • Close your eye for a few minutes — for the first minute, gently press the inside corner of your eye over your eyelid to momentarily prevent the eye drops from draining out of your eye; this will increase the effectiveness of your eye drops and reduce side effects

If you are using more than one type of eye drop, leave at least five minutes between applying the different types. 

Prescription eye drops

  • Alpha-adrenergic agonists — these reduce fluid production in your eye and increase the flow of fluid out of your eyes; they are taken twice or three times a day and include apraclonidine and brimonidine; side effects include: 
    • An irregular heart rate
    • Dry mouth
    • Fatigue
    • High blood pressure
    • Red, itchy or swollen eyes
  • Beta-blockers — these reduce fluid production in your eye; they are taken once or twice a day and include betaxolol and timolol; side effects include: 
    • Difficulty breathing
    • Fatigue
    • Impotence 
    • Lower blood pressure
    • Slower heart rate
  • Carbonic anhydrase inhibitors — these reduce fluid production in your eye; they are taken twice or three times a day and include brinzolamide and dorzolamide; side effects include: 
    • A metallic taste
    • Frequent urination
    • Tingling in your fingers and toes
  • Miotic or cholinergic agents eg pilocarpine — these increase the flow of fluid out of your eyes and are taken up to four times a day; they are not prescribed often as they need frequent daily use and have side effects including: 
    • Eye ache
    • Blurred or dim vision
    • Headaches
    • Smaller pupils
    • Shortsightedness
  • Prostaglandins — these increase the flow of fluid out of your eyes; they are taken once a day and include bimatoprost, latanoprostene bunod, latanoprost, tafluprost and travoprost; side effects include: 
    • Blurred vision 
    • Darkening of your irises, eyelashes and/or eyelid skin
    • Mildly red and stingy eyes
  • Rho kinase inhibitor — this reduces your eye pressure by suppressing the activity of enzymes that increase the fluid in your eyes (Rho kinase enzymes); it is taken once a day and is called netarsudil; side effects include: 
    • Eye discomfort
    • Deposits on your cornea
    • Red eyes

Laser treatment

If eye drops don't reduce your symptoms, your ophthalmologist may recommend laser treatment. This involves targeting a high-energy laser beam on part of your eye to reduce fluid build-up. Laser treatment is usually carried out under local anaesthetic to numb your eyes — you will therefore be awake but only feel minimal discomfort or heat during your procedure. 

Types of laser treatment include:

  • Cyclodiode laser treatment — a laser is used to destroy some of the eye tissue that produces the fluid in your eye
  • Laser iridotomy — a laser is used to create holes in your iris to help fluid flow out of your eye
  • Laser trabeculoplasty — a laser is used to open up the drainage channels in your eye to help fluid flow out

After your laser treatment, you may still need to continue using eye drops to treat your glaucoma. 


In rare cases, where eye drops and laser treatment haven't reduced your symptoms, your ophthalmologist may recommend surgery. 

The most common glaucoma surgery is a trabeculectomy, where part of the drainage channels in your eye is removed to help fluid flow out more easily. After surgery, you shouldn't be in pain and you won't need to take eye drops to treat your glaucoma anymore. 

Glaucoma surgery can be carried out under local anaesthetic or general anaesthetic. Your ophthalmologist will discuss which type of surgery is most appropriate in your case, as well as the risks and benefits. 

Other types of glaucoma surgery include:

  • Deep sclerectomy — drainage channels in your eye are widened; sometimes this is done by inserting a small device into your drainage channels
  • Trabecular stent bypass — a small tube is inserted into your eye to help fluid flow out more easily
  • Trabeculotomy — this is similar to a trabeculectomy but uses an electric current to remove a small part of the drainage channels in your eye
  • Viscocanalostomy — part of the white outer covering of your eyeball (sclera) is removed to help fluid flow out of your eye more easily 

After glaucoma surgery, your eye may be red and watery. Your vision may also be slightly blurred for up to six weeks after surgery but will return to normal. 

Your healthcare team will advise you on which activities you can and can't do during your recovery. In most cases, you will be advised to keep your eye dry and avoid driving, heavy lifting and reading for at least one week.

Treating acute angle-closure glaucoma

Acute angle-closure glaucoma is a medical emergency. You will need urgent treatment to reduce your eye pressure. This usually involves medication and laser treatment or surgery. You may have a laser peripheral iridotomy, which involves using a laser to create a small opening in your iris to help fluid flow out of your eye more easily.

Lifestyle and home remedies

To maintain healthy eyes and control high eye pressure, the following advice may help: 

  • Eat a healthy diet — this won't prevent your glaucoma getting worse but will help keep your eyes healthy; vitamins and nutrients important for eye health include copper, selenium, zinc and vitamins A, C and E
  • Exercise regularly but safely — regular exercise may help reduce eye pressure in chronic glaucoma; speak to your doctor about what exercises are appropriate and won't pose a risk to your eyes
  • Reduce caffeine — drinking lots of high-caffeine beverages may increase your eye pressure
  • Sip water often — drinking a litre or more of water quickly may temporarily increase your eye pressure; instead, drink moderate amounts throughout the day
  • Sleep with your head elevated by about 20 degrees eg using a wedge pillow — this is proven to reduce eye pressure when sleeping 
  • Take prescribed medicine exactly as instructed by your ophthalmologist to prevent further damage to your eyes

Glaucoma prevention

It isn't clear whether glaucoma can be prevented but certain self-care practices can help with early diagnosis, which can prevent or slow vision loss.

Self-care practices to follow include: 

  • Exercising regularly but safely — regular exercise may help reduce eye pressure in chronic glaucoma; speak to your doctor about what exercises are appropriate and won't pose a risk to your eyes
  • Getting regular eye tests including pupil dilation — pupil dilation allows your optometrist to examine your optic nerve; these comprehensive eye exams can detect glaucoma early before significant damage to your eyes
  • Knowing your family's eye health history — glaucoma can run in families; if a close relative has glaucoma you may be at increased risk and need more frequent eye tests
  • Taking prescribed medicine exactly as instructed by your ophthalmologist to prevent further damage to your eyes
  • Wearing eye protection when using power tools or playing high-speed racket sports — major eye injuries can cause glaucoma

Frequently asked questions

What is usually the first sign of glaucoma?

You may not have any obvious symptoms in the early stages. However, if you do have symptoms, you may notice your peripheral vision is blurry and see rainbow-coloured halos around bright lights. Later your central vision may become blurry or patchy too.

What happens if you have glaucoma?

Glaucoma causes your eye pressure to rise due to a build-up of fluid in your eyes. Fluid usually builds up because it can’t drain out of your eye properly due to blocked drainage channels. If left untreated, the rise in eye pressure permanently damages your optic nerve, which is needed for you to see — this causes vision loss.

Can glaucoma be cured?

The damage caused by glaucoma can’t be reversed but further damage can be prevented or slowed down with treatment. If you have glaucoma, you will likely need to continue with treatment for the rest of your life.

Can glaucoma be caused by stress?

There is currently no comprehensive evidence to suggest that stress directly causes glaucoma. However, high blood pressure can increase your risk of glaucoma and stress is a risk factor for high blood pressure.

What is the root cause of glaucoma?

Glaucoma is caused by a build-up of fluid in your eye, which raises your eye pressure and consequently damages your optic nerve. Your optic nerve connects your eyes to your brain and is essential for you to see.

Can watching TV cause glaucoma?

No, watching TV does not cause glaucoma.

How do I know if my glaucoma is getting worse?

If you notice your vision becoming more patchy or blurry, your glaucoma is most likely getting worse and you should see your ophthalmologist. As damage to your vision caused by glaucoma often occurs gradually, you may not notice vision changes. It is therefore important to keep up with your regular check-ups and eye tests so your ophthalmologist can detect any deterioration in your condition.

What should I avoid if I have glaucoma?

Avoid smoking and reduce your caffeine intake. Smoking is a known risk factor for several eye diseases, including glaucoma and caffeine may increase your eye pressure. Also, avoid head-down positions (ie placing your head below the level of your heart) for long stretches of time as this increases your eye pressure. Try to sleep without your eyes against the pillow or your arm; instead, sleep with your head slightly elevated by about 20 degrees.

What does vision look like with glaucoma?

Glaucoma makes your vision blurry and patchy. If left untreated, blind spots develop until you completely lose your vision.

How quickly does glaucoma progress?

This depends on the type of glaucoma you have. If you don’t get treatment, chronic glaucoma can cause blindness over several years. Acute angle-closure glaucoma can cause permanent vision loss very quickly and is a medical emergency.

What percentage of glaucoma patients go blind?

Around one in 20 people with glaucoma will go blind and around one in 10 will experience some level of vision loss despite treatment.

Are floaters a sign of glaucoma?

Floaters are not a sign of glaucoma. Floaters in your vision become more common as you get older. However, if you have noticed a sudden increase in floaters, you should see your optician as soon as possible as it could be a sign of another sight-threatening eye condition, such as a retinal detachment.

How serious is glaucoma?

Glaucoma is a serious eye condition that causes blindness if left untreated. The longer diagnosis and treatment is delayed, the higher your chance of some degree of vision loss.