The eyeball contains a fluid called aqueous humour, which is constantly produced by the eye, with any excess drained through tubes. When the fluid cannot drain properly, this causes a build-up of pressure in the eye known as the intraocular pressure (not to be confused with ocular hypertension).
Glaucoma develops when this increased pressure damages 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).
In acute glaucoma cases this pressure rises rapidly to higher levels, causing pain.
Risk factors of glaucoma
A family history of the disease
Age – chronic glaucoma affects up to two in every 100 people over 40 and around five in every 100 people over 80
Higher levels of short sightedness
Raised pressure in the eye which is called ocular hypertension (OHT)
You are also at increased risk of developing chronic glaucoma if you are of black-African or black-Caribbean origin. Acute glaucoma is 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.
What are the symptoms of glaucoma?
There are various types of glaucoma and symptoms will differ
depending on which type you have
Chronic glaucoma – this is the most common type of glaucoma and develops very slowly.
If you have chronic glaucoma, it can take a long time before you realise you have a problem with your eyesight. This is because chronic glaucoma is painless and usually damages the outer edge of the vision and works slowly inwards. Without regular checks you may not notice a problem until the glaucoma is near the centre of your vision.
Acute glaucoma – this is rare and may develop rapidly with a sudden, painful build-up of pressure in the eye. Other symptoms may include blurred vision and haloes around lights.
If you get these symptoms it is important to seek immediate assistance. Contact your optician, NHS 111 or local Accident and Emergency department.
Even if the symptoms go away you should contact your optician as soon as possible as repeat episodes can cause damage to your eyesight.
Tests for glaucoma
Eye pressure test (tonometry)
An instrument called a tonometer is used to measure the pressure inside your eye – intraocular pressure. Tonometry can be useful to identify ocular hypertension (OHT – raised pressure in the eye), which is a risk factor for chronic open-angle glaucoma.
Visual field test
You will be shown a sequence of light spots and asked which ones you can see. Some dots will appear in your peripheral vision, 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. This can be assessed in a variety of ways during your examination and it is also photographed using a retinal camera. Digital retinal photography (DRP) captures an image of your optic nerve which can be used as reference for future visits and to track any changes that may occur over time.
OCT (Optical Coherence Tomography)
OCT scans are similar to MRI and ultrasound scans and can help our opticians detect signs of glaucoma and other conditions up to four years earlier than more traditional imaging methods. The scan produces a 3D-like image that allows us to see the structures of your eye in even greater detail. Over time, your optician will be able to spot the changes that indicate the start of glaucoma. Ask your local store if they offer OCT and you can add it to your eye test.
Treatment of glaucoma
Glaucoma can be treated but early detection is important. If left untreated, glaucoma can cause visual impairment and damage that cannot be reversed. But if it’s detected and treated early enough, further damage to vision can be minimised or prevented.
So regular eye tests are essential. You should have an eye test at least every two years or more frequently if advised by your optometrist. 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.
If your optometrist suspects glaucoma, you will be referred to an ophthalmologist for further tests. If the ophthalmologist confirms a diagnosis of glaucoma, they will also be able to explain:
- How far the condition has developed
- How much damage the glaucoma has had on your eyes
- What may have caused the glaucoma
They will then be able to advise on treatment which in most cases is simply an eye drop used on a daily basis coupled with regular follow-up appointments.
Drops may be used to examine your eyes in a glaucoma appointment – these can temporarily affect your vision. Please check when making the appointment if you will be able to drive immediately after the appointment.More about glaucoma treatment
Learn more about glaucoma in our
new information hub
As part of our mission to help end avoidable sight loss, we’ve put together some helpful information about everything glaucoma – from its causes,
how it’s diagnosed, and how it can be treated.