Glaucoma is a group of eye diseases that affect the optic nerve, which connects the eye to the brain. It often affects both eyes, usually to varying degrees. As most cases won’t have any symptoms, one of the best ways to detect glaucoma is during a routine eye test - that’s why it’s so important to have one regularly.
Types of glaucoma
The main types of glaucoma are as follows:
Chronic open-angle glaucoma/primary open angle glaucoma
Chronic or primary open-angle glaucoma is the most common type of glaucoma. It develops gradually and painlessly, so an eye test is usually the only way to detect it.
Primary angle-closure glaucoma
Sometimes known as acute glaucoma, primary angle-closure glaucoma is usually treated as a medical emergency.
Unlike chronic open-angle glaucoma, primary angle-closure glaucoma happens quickly due to a sudden rise in eye pressure and can lead to sight loss if not treated quickly.
There is at least a four-times higher risk of developing glaucoma if you have a close blood relative who has it.
Congenital means a condition is present at birth and it does affect a very small number of babies.
Traumatic glaucoma can develop after an eye injury to the eye – either a blunt trauma or something that penetrates the eye. It can happen at the time of the injury or later.
What are the symptoms of glaucoma?
There are various types of glaucoma and symptoms will differ depending on which type you have.
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 develops much faster as a result of sudden pressure build-up in the eye. Although rare, it is usually painful and if often accompanied by:
- Blurred vision
- Halos around lights
- A red eye
If you get these symptoms it is important to seek immediate assistance. Contact your optician, doctor 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.
What causes glaucoma?
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.
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 can increase your chances by at least four-times
- 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 are linked to the chronic form of glaucoma and long-sighted people to the acute form
- Consistently rRaised pressure in the eye which is called ocular hypertension (OHT)
- People of African-Caribbean origin have about a four-times higher risk of chronic forms of glaucoma compared to those of European 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
- People with diabetes may be at higher risk of developing glaucoma
- Very high blood pressure can lead to an increase in intraocular pressure.
- Low blood pressure can lead to insufficient blood supply to the optic nerve which can also cause problems
Tests for glaucoma
Glaucoma will usually be diagnosed during a normal eye test. As well as looking at the overall health of your eye and the structures within it, you’ll also have a series of quick and painless tests that help to spot any signs of 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.
Treatment: managing 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 Specsavers 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 Specsavers 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.
The purpose of the eye drops is to lower the eye pressure either by reducing the amount of fluid (aqueous humour) that is produced or helping it to drain better from the eye.
Depending on the type of glaucoma, different types of laser treatment could be used. In an acute case, a procedure called an iridotomy is often used to quickly relieve the pressure and keep it lower. In non-acute cases, a selective laser trabeculoplasty (SLT) can be used to help lower the pressure, it is especially useful for people with open-angle glaucoma that hasn’t got any better using eye drops to lower the pressure.
Eye drops will often be the first treatment to try, but surgery is an option. Trabeculectomy surgery helps to slow the development of glaucoma and lower eye pressure, many other procedures may be used depending on the stage and type of the glaucoma.
Future treatment options
There are new treatments in the pipeline for glaucoma. These include a tiny stainless-steel device which allows fluid to drain out of the eye, a little probe which travels through a tiny incision and uses thermal energy to improve drainage, and a treatment called canaloplasty which uses an extremely fine catheter to enlarge the eye’s natural drainage canal and relieve pressure inside the eyes. The benefits of all these treatments include the fact that they are minimally invasive, thereby reducing pain and side effects.
Researchers are also looking at new ways to combine eye drops to make them work better and easier to use. In the longer term, research is being done into treating brain and nerve tissue to help it regenerate, as well as investigating how stem cells can help protect the optic nerve.