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 as 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
Treating glaucoma
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.
Preventing glaucoma
Attending regular Doctors appointments will help to ensure any signs of glaucoma can be detected early and 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 realise you have a problem.
Tests for glaucoma
There are several glaucoma tests that can be carried out by your doctor. 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).
th 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.
Diagnosing 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 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.
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.
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.
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.
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.
Treating glaucoma
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.
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