Glaucoma
What is it?
There are several types of glaucoma, but they all result in damaged vision through the loss of nerve fibres in the optic nerve, connecting the eye to the brain. The commonest type of glaucoma is primary open angle glaucoma (POAG).
The Symptoms
In POAG the pressure in the eyeball is too high and this causes damage to the nerve at the back of the eye which results in patches of missing vision.
However, most people are not aware that they have suffered any visual field loss from glaucoma, particularly at the early stages. Unfortunately, your visual field loss can sometimes be enough to prevent you from driving legally; if you have glaucoma in both eyes you must, by law, inform the DVLA about your condition. You will then need a specific visual field test, the Binocular Esterman Field, to see if you are still legal to drive.
Because early glaucoma has no symptoms and early treatment prevents blindness it is important to have regular eye checks with your optician. A free annual glaucoma check is available to anybody over the age of 40 by their optician if they have a 1st° relative who is known to have glaucoma.
Goldman tonometer to check eye pressure
How long does it take to become severe?
Without treatment the missing bits of vision enlarge and may eventually, after a period of several years, cause severe loss of vision.
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Ocular Hypertension
In this condition the eye pressure is higher than normal (as in glaucoma) but there is no evidence of damage to the nerve or visual field. Some patients with OHT will go on to develop glaucoma. If you have OHT your eye specialist can monitor your eyes and decide whether to begin preventative treatment to stop glaucoma developing.
Visual field test
What are the treatments?
Glaucoma is one of the conditions your optician or eye specialist will check you for. The glaucoma check involves measuring the pressure in the eye, examining the optic nerve and in some cases performing a visual field test. Photographs or OCT imaging of the optic nerve may also be helpful. Early detection allows effective treatment before much vision has been lost.
If identified early, the pressure in the eye can be lowered using eye-drops, laser treatment or surgery. In the vast majority of cases this will be enough to prevent significant loss of vision. This is vital; it is not possible to repair the damage to the nerve and vision once it has happened.
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Are there any risks?
If undetected, damage to the optical nerve is irreparable.
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Useful links
International Glaucoma Association: www.glaucoma-association.com
Driving and Vehicle Licensing Agency: www.dvla.gov.uk