Glaucoma: symptoms, causes and treatment

Most people with glaucoma notice nothing at first. The NHS says it does not usually have symptoms, that most people do not realise they have it, and that it develops slowly over many years. It usually affects both eyes, although it may be worse in one.

Glaucoma UK explains why it can go unnoticed: it most commonly affects off-centre (peripheral) vision first, while the central vision used for reading and recognising faces stays good. The only way to know is to go for regular eye health checks.

Sometimes glaucoma develops suddenly. The NHS lists the following symptoms, and says other conditions such as uveitis and eye injury can cause similar ones.

• Intense eye pain.

• A red eye and tenderness around the eyes.

• Seeing rainbow-coloured circles around bright lights.

• Blurred vision.

• Feeling sick and being sick.

• A headache.

Glaucoma UK describes it as the name of a group of eye diseases that damage the optic nerve, which transfers visual information from the eye to the brain. There are three main types: primary, secondary and developmental (glaucoma in babies and children).

The NHS says primary glaucoma is the most common type and usually develops slowly over many years. Secondary glaucoma is usually caused by another condition or an eye injury, and childhood glaucoma is a rare type that affects young children.

In many cases glaucoma is linked to raised pressure inside the eye. Glaucoma UK explains that fluid called aqueous is constantly made inside the eye and drains away through tiny channels; when drainage is restricted the pressure rises and can stress the optic nerve. Some people develop glaucoma at normal pressure (normal tension glaucoma), and others have higher than normal pressure with no detectable nerve damage, which is called ocular hypertension and needs monitoring.

The NHS says there is currently no cure, but treatments can slow down the damage and help stop vision getting worse. Treatment may include eye drops to decrease the amount of fluid in the eye and help it drain, laser treatment to decrease the amount of fluid, and surgery. You will have follow-up appointments to monitor your eyes and check that treatment is working, and it is important not to miss them.

NICE guideline NG81 covers chronic open-angle glaucoma (COAG) and ocular hypertension (OHT) in adults. It recommends offering 360-degree selective laser trabeculoplasty (SLT) to people with newly diagnosed COAG that is not advanced, and to people with newly diagnosed OHT with eye pressure of 24 mmHg or more who are at risk of visual impairment within their lifetime. NICE says people should be told that SLT can delay the need for eye drops and can reduce, but does not remove, the chance they will be needed at all.

If someone chooses not to have SLT, or it is not suitable, NICE recommends a generic prostaglandin analogue (a type of eye drop). If that is not tolerated it recommends an alternative generic prostaglandin analogue, then a beta-blocker, and then other drop classes. NICE also notes that drops from different classes may be needed at the same time to control pressure. For advanced COAG, NICE recommends offering glaucoma surgery with pharmacological augmentation as indicated, with information on the risks and benefits.

The NHS says glaucoma is usually caused by a build-up of pressure in the eye, which happens when fluid cannot drain as it should. The pressure damages the optic nerve. Sometimes the pressure is in the normal range but damage still occurs, and it is not always known why.

Glaucoma UK says anyone can develop glaucoma, but some things make it more likely. It is uncommon below age 40, and rises from around 1 in 50 people over 40 to around 5 in 50 people over 75. Its list of risk factors is below.

• Age: more common as people get older.

• Family history: Glaucoma UK says brothers, sisters and children may be up to 10 times more likely to develop it, depending on the type.

• Ethnicity: people of black African and Caribbean origin and people of Asian origin are more likely than people of European origin to develop glaucoma.

• Short sight (myopia) is linked to primary open angle glaucoma, and long sight to primary angle closure.

• High blood pressure is linked to high eye pressure; Glaucoma UK says low blood pressure might reduce blood flow to the optic nerve.

• Diabetes: the NHS and Glaucoma UK both list it as a possible risk factor.

The NHS says glaucoma is usually found during a routine eye test, often before it causes symptoms. Glaucoma UK explains that an optometrist will not diagnose glaucoma, but can find warning signs and refer you to a specialist service.

At the eye test the optometrist may carry out a visual field test (to check peripheral vision), an eye pressure test (often the air-puff test) and an optic nerve assessment, sometimes with a photograph. A referral does not mean you definitely have glaucoma. The specialist repeats some of these tests, looks at other risk factors and decides whether you have glaucoma or are at increased risk, and whether you need treatment.

NICE recommends that people referred for suspected COAG are offered a visual field test, an optic nerve assessment, eye pressure measurement and assessment of the drainage angle, and that optical coherence tomography (OCT) of the optic nerve head is used if available.

The NHS describes childhood glaucoma as a rare type that affects young children. Glaucoma UK calls glaucoma in babies and children developmental glaucoma, and produces dedicated information for families.

If you are worried about a child's eyes or vision, see a GP or optician. A sudden onset of eye pain or redness in anyone, including a child, should be treated as an emergency.

The NHS says that if glaucoma is diagnosed and treated early, it may not change your vision much, but sometimes sight is affected and in rare cases people lose their sight. For many people, managing glaucoma means using eye drops daily and attending regular eye clinic appointments.

Glaucoma UK says it is a life-long, chronic condition, but that huge advances mean that in the UK the vast majority of people with glaucoma will keep useful sight for life. Support is available from Glaucoma UK and the RNIB if you have some sight loss or find it hard to come to terms with the diagnosis.

The NHS says to call 999 or go to A&E if you develop symptoms of glaucoma suddenly: intense eye pain, a red eye, rainbow-coloured circles around lights, blurred vision, nausea or a headache. It describes this as a medical emergency that may require immediate treatment, and says not to drive yourself to A&E. Ask someone to drive you or call 999, and take any medicines you use.

See a GP or optician if you have any concerns about your vision. If you have already been diagnosed and your eye becomes painful or red, or your vision changes after laser or surgery, contact your eye clinic for advice.

On the NHS, glaucoma is usually picked up at an optician, after which you may be referred to a hospital eye service or, in some areas, a specially trained community optometrist, as Glaucoma UK describes. Some people are eligible for free NHS eye tests, and the NHS says you can find out more through the NHS sight test information.

Private ophthalmology clinics offer the same tests and treatments, and some people use them for quicker appointments. Whichever route you use, ask who will monitor your pressure, visual fields and nerve over the long term, and make sure your results are shared with your optometrist and GP.