Glaucoma is a condition which can affect sight, usually due to build up of pressure within the eye.
Glaucoma often affects both eyes, usually to varying degrees. One eye may develop glaucoma quicker than the other.
The eyeball contains a fluid called aqueous humour which is constantly produced by the eye, with any excess drained though tubes.
Glaucoma develops when the fluid cannot drain properly and pressure builds up, known as the 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).
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 mainly occurs as a result of an eye injury or another eye condition, such uveitis (inflammation of the middle layer of the eye)
• developmental glaucoma (congenital glaucoma) – a rare but sometimes serious type of glaucoma which occurs in very young children, caused by an abnormality of the eye.
How common is glaucoma?
In England and Wales, it’s estimated more than 500,000 people have glaucoma but many more people may not know they have the condition.
Chronic open-angle glaucoma affects up to two in every 100 people over 40 years old and around five in every 100 people over 80 years old.
You are also at increased risk of developing open-angle glaucoma if you are of black-African or black-Caribbean origin.
Some 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 of glaucoma
Symptoms of the different types of glaucoma are explained below.
There are four main types of glaucoma:
• chronic open-angle glaucoma – the most common type which often has few symptoms
• acute angle-closure glaucoma – which often has severe symptoms
• secondary glaucoma – caused by other conditions or eye treatments
• developmental glaucoma – a rare condition affecting young babies
Chronic open-angle glaucoma
In cases of chronic glaucoma, there are usually no noticeable symptoms because the condition develops very slowly. People don’t often 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
• 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’s important to contact your GP straight away if you have any of the above symptoms, because early treatment can prevent further damage occurring. This is an emergency and you should seek urgent advice.
Secondary glaucoma is caused by other conditions, such as uveitis (inflammation of the middle layer of the eye). It can also be caused by eye injuries and certain treatments, such as medication or operations.
It’s 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.
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
Attending regular optician appointments will help to ensure any signs of glaucoma can be detected early and allow treatment to begin.
Glaucoma can be treated with eye drops, laser treatment or surgery. But 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’s diagnosed and treated early enough, further damage to vision can be prevented.
Treatment aims to reduce the pressure in the affected eye, called intraocular pressure.
Any damage to your vision caused by glaucoma can’t be repaired so it’s important to get an early diagnosis and treatment to prevent further damage.
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’s 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.
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
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
• sensitivity to light
Some types of prostaglandin analogues that you may be prescribed include:
It is thought that
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:
• a heart condition, such as heart block
Some types of beta-blockers you may be prescribed include:
• betaxolol hydrochloride
• levobunolol hydrochloride
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:
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:
• high blood pressure
• heart disease
A type of sympathomimetic that you may be prescribed is brimonidine tartrate.
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, 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.
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 are awake) or general anaesthetic (you are 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 either:
• mitomycin C
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.
But many specialists 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:
• eye drops – see above for further details
• 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
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.
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:
• heart disease
• high blood pressure
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 four months or up to 12-24 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