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).
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 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 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
Causes of glaucoma
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’s 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’s often unclear why the drainage tubes become blocked or why other parts of the eye obstruct the tubes.
There are a number of things that can increase your risk of developing glaucoma:
- age (glaucoma becomes more likely as you get older) – in the UK, 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
- ethnic origin – people of African or Afro-Caribbean origin are at increased risk of developing chronic open-angle glaucoma and 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) – your optometrist will be able to diagnose OHT, which increases your risk of developing chronic open-angle 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 may be at increased risk of developing glaucoma
It’s important to have regular eye tests so eye problems, such as glaucoma, can be diagnosed and treated as early as possible.
If you have glaucoma, it can take a long time before you realize 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.
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 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 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
A visual field test – sometimes called 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 can’t 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.
If your optometrist suspects glaucoma, you will be referred to an ophthalmologist for further tests. Your ophthalmologist 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.
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 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.
If the use of eye drops does not improve your symptoms, a different type of treatment may be recommended, such as laser treatment, Acupuncture 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.
Acupuncture although not known to some people is highly effective in the treatment of Glaucoma. The using of needles on various points of the body can control the spread of glaucoma in the eye’s drainage system, thereby making the treatment more effective.
it’s always better to visit your Acupuncturist when you start noticing strange symptoms about your eyes. Acute stages are more liable to heal faster than chronic stages of glaucoma, nonetheless both can be treated.
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
Complications with glaucoma
The main complication of glaucoma is loss of vision that can’t be repaired. This is why early diagnosis and treatment is so important.
Loss of vision
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.
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.
If you have glaucoma, it could affect your ability to drive. It’s your legal obligation to inform the Driver and Vehicle Licensing Agency (DVLA) about a medical condition that could affect your driving ability.