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. In New Zealand, it's estimated more than 91,000 people have glaucoma but as many as 50% do not know they have the condition.
What are the symptoms of glaucoma?
Chronic glaucoma – this is the most common type of glaucoma and develops very slowly. Chronic glaucoma is painless and usually affects the outer edge of vision first, then 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 less common 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 have any of these symptoms it is important to seek immediate medical care from an optometrist, GP or a hospital emergency department. Even if these symptoms go away, you should still contact your optometrist as soon as possible for assessment, as acute episodes can occur many times and can cause damage to your eyesight
Visual symptoms of glaucoma
These images show the difference in vision typically expected between someone with normal vision, someone with mild glaucoma, and someone with more advanced glaucoma.
Images used with permission from the International Glaucoma Association.
What causes glaucoma?
The eyeball contains a fluid called aqueous humour, which is constantly produced by the eye, with any excess drained though 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
- People with a direct family history have a 25% chance of developing 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 glaucomas 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.
Tests for glaucoma
There are several tests that can be carried out by your Specsavers optometrist in addition to the usual examinations carried out during an eye test. They are painless and quite quick.
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.
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.
Proud to work with Glaucoma New Zealand
We are proud to work with Glaucoma New Zealand to help raise awareness of glaucoma, improve glaucoma detection rates and avoid preventable vision loss from glaucoma. While glaucoma has no early symptoms, advanced glaucoma can lead to vision loss and blindness. However, if detected early a simple treatment regime of one eye drop a day can stop the disease and prevent further deterioration of vision.
In New Zealand around 91,000 people currently have glaucoma and don't know it. Together with Glaucoma New Zealand, we are working to raise awareness of glaucoma and encourage Kiwis to have regular eye tests.
Who is Glaucoma New Zealand?
Glaucoma New Zealand is a charitable trust whose mission is to eliminate blindness from glaucoma. They work to enhance public awareness about glaucoma, support and inform people with glaucoma, educate eye health workers to assure high quality services, and facilitate research into glaucoma.
Specsavers is proud to support and work with Glaucoma New Zealand. We both believe the best way to give people with glaucoma hope is to detect glaucoma before they have lost any of their sight, initiate treatment and provide ongoing monitoring to ensure they remain on their treatment plan in order to preserve their vision for the rest of their life.