Glaucoma

Glaucoma is a term that describes a group of eye conditions that affect vision.

Introduction

Glaucoma is a term that describes a group of eye conditions that affect vision. Glaucoma often affects both eyes, usually in varying degrees. One eye may develop glaucoma quicker than the other.

Glaucoma occurs when the drainage tubes (trabecular meshwork) within the eye become slightly blocked. This prevents eye fluid (aqueous humour) from draining properly.

When the fluid cannot drain properly, pressure builds up. This is called intraocular pressure. This can damage the optic nerve (which connects the eye to the brain) and the nerve fibres from the retina (the light-sensitive nerve tissue that lines the back of the eye).

Read more information about the causes of glaucoma.

Types of glaucoma

There are four main types of glaucoma:

  • chronic open-angle glaucoma – this is the most common type of glaucoma and develops very slowly
  • primary angle-closure glaucoma – this is rare and can occur slowly (chronic) or may develop rapidly (acute) with a sudden, painful build-up of pressure in the eye
  • secondary glaucoma – this occurs as a result of an eye injury or another eye condition, such as uveitis (inflammation of the middle layer of the eye)
  • developmental glaucoma (congenital glaucoma) – this is rare but can be serious. It is usually present at birth or develops shortly after birth. It is caused by an abnormality of the eye

Read more information about the symptoms of glaucoma.

Treating glaucoma

Glaucoma can be treated with eye drops, laser treatment or surgery. However, early diagnosis is important because any damage to the eyes cannot be reversed. Treatment aims to control the condition and minimise future damage.

If left untreated, glaucoma can cause visual impairment. But if it is diagnosed and treated early enough, further damage to vision can be prevented.

Read more about how glaucoma is treated.

Preventing glaucoma

Attending regular optician appointments will help to ensure any signs of glaucoma can be detected early and allow treatment to begin. Read about how glaucoma is diagnosed.

How common is glaucoma?

Among white Europeans, about 1 in 50 people over 40 years of age and 1 in 10 people over 75 years of age have chronic open-angle glaucoma.

You are also at increased risk of developing open-angle glaucoma if you are of black-African or black-Caribbean origin.

The other types of glaucoma, such as acute angle-closure glaucoma, are much less common. However, people of Asian origin are more at risk of getting this type of glaucoma compared with those from other ethnic groups.

Symptoms

Symptoms of the different types of glaucoma are explained below.

Chronic open-angle glaucoma

In cases of chronic glaucoma, there are usually no noticeable symptoms because the condition develops very slowly. People often do not realise their sight is being damaged because the first part of the eye to be affected is the outer field of vision (peripheral vision). Vision is lost from the outer rim of the eye, slowly working inwards towards the centre.

Changes in vision are often linked to getting older, which is why it is so important to have your eyes checked regularly. You should have an eye test at least every two years, or more frequently if your optometrist (healthcare professional who tests sight) recommends it.

Acute angle-closure glaucoma

Acute angle-closure glaucoma develops rapidly. Symptoms are often severe. They include:

  • intense pain
  • redness of the eye
  • headache
  • tender eye area
  • seeing halos or 'rainbow-like' rings around lights
  • misty vision
  • loss of vision in one or both eyes that progresses very quickly

As a result of these symptoms, some people may also feel sick or be sick.

Symptoms of acute glaucoma are not constant. They can last for one or two hours before disappearing again. But each time the symptoms occur, your vision is damaged a little more.

It is important to contact your doctor straight away if you have any of the above symptoms, because early treatment can prevent further damage occurring.

If you have symptoms outside your doctor's normal working hours, visit your nearest accident and emergency (A&E) department. The healthcare professionals at A&E will relieve the pressure within your eye and treat any pain.

Secondary glaucoma

Secondary glaucoma is caused by other conditions or eye injuries, such as uveitis (inflammation of the middle layer of the eye). It is possible for the symptoms of glaucoma to be confused with the symptoms of the other condition. For example, uveitis often causes painful eyes and headaches.

However, the glaucoma may still cause misty vision and rings or halos around lights.

Developmental glaucoma

Recognising the symptoms of developmental glaucoma (also known as congenital glaucoma) can be difficult due to the young age of the baby or child.

However, your child may display symptoms, such as:

  • large eyes due to the pressure in the eyes causing them to expand
  • being sensitive to light (photophobia)
  • having a cloudy appearance to their eyes
  • having watery eyes
  • jerky movements of the eyes
  • having a squint, which is an eye condition that causes one of the eyes to turn inwards, outwards or upwards, while the other eye looks forward

If you notice any of these symptoms, visit your doctor or optometrist as soon as possible.

Causes

Glaucoma is caused by a blockage in part of the eye. This prevents fluid draining out of the eye and increases pressure in the eye, called intraocular pressure.

How the eye works

The eyeball is filled with a watery substance called aqueous humour, which creates pressure in the eye to give it shape. In healthy eyes, this fluid constantly flows in and out of the eye. It drains back into the bloodstream at the same rate that it is produced to maintain the correct pressure.

Glaucoma occurs when the drainage tubes (trabecular meshwork) within the eye become slightly blocked, preventing the aqueous humour from draining properly. An obstruction within the eye, such as a blood vessel blocking the trabecular meshwork, can also prevent fluid from draining properly.

When the fluid cannot drain properly, the pressure in the eye builds up and can damage the optic nerve (the nerve that connects the eye to the brain) and the nerve fibres from the retina (the light-sensitive nerve tissue that lines the back of the eye).

It is often unclear why the drainage tubes become blocked or why other parts of the eye obstruct the tubes.

Increased risk

There are a number of things that can increase your risk of developing glaucoma:

  • ae – glaucoma becomes more likely as you get older. Cronic open-angle glaucoma affects one to two people in every 100 who are over 40 years old, and four to five people in every 100 who are over 80 years old
  • ethnic origin*– people of African or Afro-Caribbean origin are at increased risk of developing chronic open-angle glaucoma. People of Asian origin are at increased risk of developing acute angle-closure glaucoma
  • short sightedness (myopia) – people who are short-sighted are more likely to develop chronic open-angle glaucoma
  • ocular hypertension (OHT – raised pressure in the eye). People with OHT are at increased risk of developing chronic open-angle glaucoma. Your optometrist will be able to diagnose OHT (see diagnosing glaucoma)
  • family history – if you have a close relative, such as a parent, brother or sister who has glaucoma, you are at increased risk of developing the condition yourself
  • medical history – people with diabetes, which is a condition caused by too much glucose in the blood, may be at increased risk of developing glaucoma

Diagnosis

If you have glaucoma, it can take a long time before you realise you have a problem with your eyesight. This is because glaucoma usually damages the outer edge of the eye and works slowly inwards. You may not notice a problem until the glaucoma is near the centre of your eye.

It is therefore important to have regular eye tests so that problems can be detected and treated as early as possible.

You should have an eye test at least every two years or more frequently if advised by your optometrist (a healthcare professional who tests sight). For example, they may suggest you have more frequent eye tests if you have a close blood relative with glaucoma, such as a parent, brother or sister.

Tests for glaucoma

There are several glaucoma tests that can be carried out by your optometrist. They are painless and quite quick. The tests should be carried out during the same appointment to ensure results are as accurate as possible.

These tests are explained below.

Eye pressure test (tonometry)

An eye pressure test (tonometry) uses an instrument called a tonometer to measure the pressure inside your eye. A small amount of anaesthetic (painkilling medication) and dye is placed onto the transparent layer of tissue that covers the front of the eye (your cornea). A blue light from the head of the tonometer is held against your eye to measure the intraocular pressure.

Tonometry can diagnose ocular hypertension (OHT – raised pressure in the eye), which is a risk factor for chronic open-angle glaucoma.

Central corneal thickness

The thickness of your cornea will be measured because this is thought to affect how the intraocular pressure is interpreted.

Gonioscopy

Gonioscopy is an examination of the front outer edge of your eye, between the cornea and the iris (the coloured part of your eye). This is the area where the fluid should drain out of your eye. A gonioscopy can help to determine whether this angle is open or closed (blocked).

Visual field test (perimetry)

A visual field test (perimetry) checks for missing areas of vision. You will be shown a sequence of light spots and asked which ones you can see. Some dots will appear in your peripheral vision (around the sides of your eyeball), which is where glaucoma begins.

If you cannot see the spots in your peripheral vision, it may indicate the glaucoma has damaged your vision.

Optic nerve assessment

Your optic nerve connects your eye to your brain. Your optometrist will use eye drops to enlarge your pupils. They will then examine your eyes using a slit lamp (a microscope with a very bright light) and assess whether your optic nerve has been damaged by the glaucoma.

The eye drops used to widen your pupils could affect your ability to drive. You should make alternative arrangements for getting home after your appointment.

Referral

If your optometrists suspects glaucoma, they will refer you to an ophthalmologist for further tests. Your ophthalmologist will confirm your diagnosis and find out:

  • how developed the glaucoma is
  • 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).

In some cases, your ophthalmologist will continue to treat you. But if you have chronic open-angle glaucoma, you may be referred back to your optometrist who will continue your treatment.

Treatment

Any damage to your vision caused by glaucoma cannot be repaired. This is why it is so important to diagnose glaucoma early so it can be treated and further damage can be prevented.

The aim of treatment for every type of glaucoma is to reduce the pressure in the affected eye, called intraocular pressure.

Eye drops

Chronic open-angle glaucoma is often treated using eye drops. There are several different types of eye drops available, the type prescribed may depend on:

  • how your condition is progressing
  • whether you have other medical conditions
  • whether you are taking any other medications
  • whether the eye drops cause side effects when you use them

Using eye drops

It is important to use eye drops as directed. Even if you have not yet noticed any problems with your vision, without treatment glaucoma can cause permanent vision loss.

To use 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 lid
  • close your eye and keep it closed for several minutes

If you are using two different types of eye drops, allow at least five to 10 minutes between using the different types.

Also follow any other advice your optometrist or ophthalmologist has given you.

Contact lenses

If you usually wear contact lenses and have been prescribed eye drops, you may need to stop wearing your lenses and wear glasses instead. This is because medication in the eye drops can build up in the lenses and may harm your eyes. You should discuss this with healthcare professionals treating you.

Types of eye drops

The different types of eye drops are described below. You can read [medicines information] for more details about your medication.

Prostaglandin analogue

Prostaglandin analogues increase the flow of fluid (aqueous humour) out of your eye, which reduces the pressure within your eye (the intraocular pressure). These eye drops are usually used once a day. Side effects include:

  • enlarged blood vessels in the white part of your eye, making your eye look red
  • changes to your eye colour – it often gets darker
  • eyelashes growing thicker and darker
  • eye pain and irritation
  • blepharitis – a condition where the rims of your eyelids become red and swollen
  • dry eyes
  • headaches
  • sensitivity to light

Some types of prostaglandin analogues that you may be prescribed include:

  • [latanoprost]
  • [bimatoprost]
  • [tafluprost]
  • [travoprost]

Beta-blockers

It is thought that beta-blockers reduce intraocular pressure by slowing down the production of aqueous humour in your eye. They are used once or twice a day and can cause side effects such as:

  • a stinging or burning sensation in your eye
  • dry eyes
  • itchy eyes

Beta-blockers can make some medical conditions worse, so do not use them if you have:

Some types of beta-blockers you may be prescribed include:

  • [betaxolol hydrochloride]
  • [levobunolol hydrochloride]
  • [timolol]

Carbonic anhydrase inhibitors

Carbonic anhydrase inhibitors reduce the amount of aqueous humour produced in your eye, which reduces intraocular pressure. These drops are used two or three times a day and may cause:

  • a bitter taste in your mouth
  • nausea (feeling sick)
  • a dry mouth
  • eye irritation

Some types of carbonic anhydrase inhibitors you may be prescribed include:

  • [brinzolamide]
  • [dorzolamide]

Sympathomimetics

Sympathomimetics are thought to reduce the rate of production of aqueous humour and increase the flow of aqueous humour out of the eyes. These eye drops are used twice a day and may cause your eyes to become painful and red.

Some types of sympathomimetics can only be used with caution in people who have:

A type of sympathomimetic that you may be prescribed is [brimonidine tartrate].

Other treatments

If the use of eye drops does not improve your symptoms, a different type of treatment may be recommended, such as laser treatment or surgery. These are described in more detail below.

Laser treatment

Laser treatment, which uses high energy beams of light, can be used to open up the blocked trabecular meshwork (drainage tubes) within your eye. This is called laser trabeculoplasty.

Anaesthetic (painkilling) eye drops will be put into your eye and a special lens placed in front of your eye. The laser will be shone through the lens and will make small holes in the trabecular meshwork. This allows more fluid to drain out of your eye and reduces the intraocular pressure.

An alternative to laser trabeculoplasty is cyclodiode laser treatment. This involves destroying some of the tissue in the eye that produces aqueous humour. It creates less fluid in the eye, which reduces the intraocular pressure.

Laser treatments are usually quick and painless, although during the procedure you may feel a brief twinge of pain or heat. You may still need to use eye drops (see above) after having laser treatment.

Surgery

A trabeculectomy is the most common type of glaucoma surgery. It involves removing part of the trabecular meshwork to allow fluid to flow through the eye's drainage system. The procedure will be carried out under local anaesthetic (you will still be conscious) or general anaesthetic (you will be unconscious).

Other types of surgery include:

  • a viscocanalostomy – this operation removes part of the sclera (the white outer covering of the eyeball), enabling the fluid to filter out of your eye and into your body
  • a deep sclerectomy operation – this operation involves implanting a tiny device inside your eye to widen the trabecular meshwork
  • an aqueous shunt implant – this operation involves placing a tube device into your eye to increase the drainage of fluid out of your eye

Speak to your surgeon to find out more about your procedure and risks involved.

If you are having surgery, your surgeon may choose to use anti-scarring medicines. These can improve the success of the operation by preventing scar tissue forming as your eye heals. You may be prescribed:

  • mitomycin C or
  • 5-fluorouracil

These medications are unlicensed for the treatment of glaucoma. This means that the manufacturers of these medications have not applied for a licence for their medication to be used to treat glaucoma. In other words, the medications have not undergone clinical trials (research that tests one treatment against another) to see if they are effective and safe in treating glaucoma.

Many experts will use an unlicensed medication if they think the medication is likely to be effective and benefits of treatment outweigh associated risk.

If your ophthalmologist is considering prescribing an unlicensed medication, they should inform you that it is unlicensed, and discuss possible risks and benefits with you.

Acute angle-closure glaucoma

As acute glaucoma develops rapidly, the condition needs to be treated quickly. The most common forms of treatment for this type of glaucoma include:

  • systemic medicines – these are injected into your bloodstream to quickly reduce the pressure in your eye
  • laser treatment (called laser iridotomy) – this uses high-energy beams of light to create holes in your iris (coloured part of the eye) to open the angle and enable fluid to flow; both eyes may need to be treated, even if only one has acute angle-closure glaucoma, because this form of glaucoma may develop in both eyes at some point
  • surgery – a trabeculectomy (surgery to remove part of the drainage tubes) is the most common form of surgery for acute glaucoma
  • eye drops – see above for further details

If you also have a cataract (a cloudy patch in the lens of your eye) removing it may open the angle in your eye and control the intraocular pressure.

Read about cataract surgery for more information about this procedure.

Miotics

Acute angle-closure glaucoma may also be treated with a medication called a miotic, such as pilocarpine. Miotics work by opening up the blocked trabecular meshwork, which should improve the drainage of aqueous humour out of your eye. You may need to use these eye drops up to four times a day.

Miotics should be used with caution in people who have certain medical conditions, including:

Miotics can also cause side effects, such as:

  • a headache, which may be severe during the first two to four weeks of treatment
  • burning or itchy eyes
  • blurred vision, which may affect your ability to drive

Treating other types of glaucoma

For other types of glaucoma, your specialist will usually recommend eye drops, laser treatment or surgery. Your treatment will depend on the type of glaucoma you have and how advanced it is.

Monitoring your condition

If you have been diagnosed with glaucoma your condition will be closely monitored to check for further damage to your vision.

Depending on how your glaucoma is progressing, you may need further appointments every one to 4 months or up to 12 to 24 months apart. These will either be with:

  • an optometrist – a healthcare professional who examines eyes, tests vision and is trained to recognise eye diseases and vision defects
  • an ophthalmologist – a medical doctor who specialises in eye diseases and their treatment and surgery

Complications

Loss of vision is the main complication of glaucoma. This is why early diagnosis and treatment is so important.

Loss of vision

Glaucoma is responsible for one in 10 cases of visual impairment. If you have some loss of vision due to glaucoma, more information is available on the Royal National Institute of Blind People (RNIB) website. The RNIB offers advice about:

  • living with sight loss
  • registering your sight loss – this may allow you to access certain benefits

Complications from treatment

If you have surgery to treat glaucoma, there is always a risk of infection. Most infections can be treated with a course of antibiotics (medication to treat bacterial infections).

You may also have a reaction to certain types of eye drops. Speak to the healthcare professionals treating you if you feel unwell while being treated for glaucoma.

Driving

If you have glaucoma, it could affect your ability to drive. It is your legal obligation to inform your driver licence issuer about a medical condition that could affect your driving ability.

Aruna's story

Glaucoma is a group of eye conditions that affect vision. Aruna talks about her diagnosis and subsequent treatment.

Linda's story

Linda Moore, 62, has had open angular glaucoma since she was 39. She runs the Poole Glaucoma Support Group, which supports people with glaucoma in their local area.

"I had no idea I had glaucoma until I went for a routine eye examination at the age of 39. I didn’t have any symptoms at all, but after my eye test the optician just said: ‘You’ve got early-stage glaucoma. I’m going to give you a letter to give to your doctor, and you’ll need to see a consultant.’

"It was a shock to find out there was something wrong. I know now that I’ve got a family history – one of my aunts had it – but at the time I didn’t know anything about it. I was aware that it’s a disease of the eye, but I didn’t realise it could cause blindness.

"To be honest, when I saw the consultant I wasn’t given much more information. I received some eye drops (glaucoma causes the tear ducts to dry up, so the drops help with that). I was told I'd have to take them for the rest of my life, but that was it. I’ve discovered through the support group that many people find there’s a lack of information during the first consultant appointment.

"One of the major causes of glaucoma is a rise in the pressure in your eye, which weakens the optic nerve and possibly damages it. At one point, the pressure in my eyes kept rising and I was advised to have laser treatment to lower it. The treatment took place at the Eye Unit at Bournemouth Hospital. It wasn’t particularly comfortable or painless, but it was over quickly, and it worked.

"I know I’ve been very lucky. I’ve had good consultants who've kept a careful watch on the results of my six-monthly check-ups, and I’ve managed to maintain reasonable eyesight. I’ve had to stop giving blood, and I can’t take certain medications – but they’re the only restrictions so far. My eyes are tested regularly, and I need new glasses every two years. But having regular eye tests is absolutely crucial. I know of people whose eyesight got worse almost overnight due to their glaucoma being undiagnosed or unchecked."

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