Glaucoma is a group of eye diseases that can gradually steal sight without warning. In the early stages of the disease, there may be no symptoms. Experts estimate that half of the people affected by glaucoma may not know they have it.
The optic nerve is a bundle of more than a million nerve fibres at the back of your eye. It's like an electric cable made up of thousands of individual wires carrying the images from the inside back wall of your eyeball (retina) to your brain.
Blind spots develop in your visual field when the optic nerve deteriorates, usually starting with your peripheral (side) vision. If left untreated, glaucoma may lead to blindness in both eyes. There is no cure for glaucoma yet. However, medication or surgery can slow or prevent further vision loss. The appropriate treatment depends upon the type of glaucoma among other factors. Early detection is vital to stopping the progress of the disease.
It was once thought that high pressure within the eye, also known as intraocular pressure or IOP, was the main cause of this optic nerve damage. Although IOP is clearly a risk factor, we now know that other factors are also involved because even people with “normal” levels of pressure can experience vision loss from glaucoma. Fortunately, medical advances have made it easier to diagnose and treat glaucoma. If detected and treated early, glaucoma need not cause even moderate vision loss. But having Glaucoma does mean regular monitoring and treatment for the rest of your life.
Risk factors for primary Open-angle Glaucoma include increasing age and a family history of glaucoma. It is more common in Afro-Caribbean people. There has also been a suggestion that diabetes is a risk factor for glaucoma.
Screening tests are important to detect glaucoma before there is significant loss of vision. An optometrist (optician) can do these during a sight test. Ideally, everyone over 35 should have their eyes checked for glaucoma every two years. People aged 40 or over who have a family history of glaucoma are entitled to free eye tests.
There are three types of simple, painless tests that an optometrist can do:
- Look at the back of the eye using a special torch (ophthalmoscope). Damage to the optic nerve can be seen at the back of the eye.
- Measure the internal pressure of the eye (tonometry). This is done with a device that blows a small puff of air onto the eyeball.
- Measure the field of vision, by showing a sequence of spots of lights and asking which can be seen.
People who are found to have signs of glaucoma can be referred to a specialist eye doctor (an ophthalmologist) for confirmation and treatment.
Treatment for glaucoma aims to lower the internal pressure of the eye and prevent any loss of vision, or any further deterioration in vision. Options include medicine given as eye drops, laser treatment and surgery. Treatment cannot reverse any existing optic nerve damage, so it won’t improve sight that has already deteriorated.
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