What is it?
Glaucoma is the name given to a group of eye diseases in which the optic nerve at the back of the eye is damaged. This process progresses very slowly and destroys vision gradually, starting with the peripheral (side) vision.
It is a major cause of sight loss in Australia, and it is as common as diabetes.
About 3% of Australians have glaucoma but, because there are generally no warning signs, only about half of them have been diagnosed. One of the most sinister characteristics of glaucoma is that a person with glaucoma is unaware of any visual problems until a majority of nerve fibres have been irreversibly damaged. This is why we encourage everyone to undertake a comprehensive eye check every two years. The tests for glaucoma are simple and painless.
In some people this damage may be due to an increased pressure inside the eye – a result of blockage of the circulation of the aqueous, or its drainage. In other patients the damage may be caused by poor blood supply to the vital optic nerve fibres, a weakness in the structure of the nerve, and/or a problem in the health of the nerve fibre themselves.
Who is at Risk?
Although anyone can get glaucoma, some people have a higher risk. Those with:
- A family history of glaucoma
- Short sightedness (myopia)
- Eye injuries
- High Blood pressure
- Past or present use of cortisone drugs (steroids)
What are the symptoms?
Glaucoma has no symptoms until around 40% of the optic nerve fibres are damaged. This damage is irreversible, progressive and usually relentless. Treatment cannot recover what has been lost, but it can arrest, or at least, slow down the damage process. That is why it is so important to detect the problem as early as possible.
How is glaucoma detected?
Regular eye examinations are the best way to detect glaucoma early.
A glaucoma test may include all or some of the following:
- Optic nerve check with an ophthalmoscope/funduscopy lens
- Eye pressure check (tonometry)
- Digital Fundus Photos – these enable us to examine the optic nerve head for early changes in appearance which might suggest glaucoma. They are particularly useful for picking up small changes in eyes at risk.
- Pachymetry- this measures the thickness of the cornea (the clear window at the front of the eye) and allows us to adjust the eye pressure reading appropriately.
- OCT (Ocular Coherence Tomography) scans the retina down to the cellular level and aids in detection of early damage to the optic nerve fibre layer.
- Visual field assessment – this tests the sensitivity of our peripheral vision, where glaucoma strikes first.
There is no one test which is diagnostic for glaucoma and in most cases the doctor will rely on all of the above information when deciding when to treat.
Can glaucoma be treated?
Although there is no cure for glaucoma it can usually be controlled and further loss of sight either prevented or at least slowed down.
- Eye Drops – these are the most common form of treatment and must be used regularly. In some cases pills are prescribed.
- Laser (laser trabeculoplasty) – this is performed when eye drops do not stop deterioration in the field of vision. Laser is used to try to unblock or increase the filtration of the aqueous through the trabecular meshwork, hence lowering the intraocular pressure.
- Surgery (trabeculectomy) – this is performed usually after eye drops and laser have failed to control the eye pressure. Surgery is conducted on the trabecular meshwork to increase the outflow of the aqueous, lowering the intraocular pressure.
Treatment can save remaining vision but it does not improve eye sight.
For more information contact us.