This is a disease of the eye, where the normal fluid pressure inside the eye gradually increases, leading to problems with vision or even blindness on occasions.
The basic problem in glaucoma is in the small space at the front of the eye, called the anterior chamber. There is normally a steady flow of clear eye fluid in and out of this chamber, bathing and nourishing the eye. For reasons which still remain unclear, in glaucoma this fluid begins to drain out too slowly and so the fluid pressure slowly builds up in the eye. This excess pressure causes damage to the optic nerve, which connects the light-sensitive retina at the back of the eye to the brain. It is the health of this optic nerve which is necessary for healthy vision and so progressive damage to it from glaucoma slowly damages the eyesight. Most people suffer from a form of glaucoma called 'open-angle glaucoma'.
What Are Glaucoma Symptoms And Signs?
Initially there are no symptoms in open - angle glaucoma. There is no pain, and the vision is normal. However, if the glaucoma remains untreated, a person may notice that although they can see things directly in front of them clearly, anything to one side of their vision appears blurred or foggy. They may fail to see objects to one side of them, and feel as if they are 'looking through a tunnel'. Over time, their vision may gradually disappear to nothing.
Will I Have Any Tests Or Investigations?
Specialized tests are vital for the diagnosis of glaucoma to be accurately made.
There are 4 main tests;
1. Visual acuity. This involves using the well-known 'doctor's eye chart' with letters of different sizes on it to measure how well you see at various distances.
2. Visual field. This important test measures your side (peripheral) vision, the loss of which is an early sign of glaucoma.
3. Pupil dilation. Special drops are put into the eye to dilate the centre of it and allow for the optic nerve to be examined. This means you will have blurred vision for some hours until the drops wear off, and you should not drive in this time.
4. Tonometry.There are a number of different types of this test, all of which are designed to measure the fluid pressure inside the eye. A common type is the fair puff' test which measures the resistance of the eye to a puff of air, and is quick and painless.
What Treatment Might I Need?
Glaucoma is readily treatable, although not curable. The usual treatment is medicines, either in the form of eyedrops or pills. Some of these help to drain excess fluid from inside the eye, and others cause less fluid to be produced in the first place. These have the disadvantage of having to be taken several times each day, and they may also become less effective with time. It is important that your doctor knows any other medicines you may be taking before starting such treatment in order to avoid drug reactions or side effects. Laser surgery is becoming an increasingly popular treatment option. In this case, a strong beam of light (the laser) is focused on the anterior chamber at the front of the eye. This is painless because the eye has been numbed first with anaesthetic eye drops.
You may see little flashes of red or green light, and the laser makes up to 100 evenly spaced burns around the anterior chamber. These allow fluid to drain more easily out of the chamber and so reduce the eye pressure. This is very effective at treating glaucoma, but pressure may slowly increase again after 1 -2 years in some patients. If medication and laser surgery have no effect, 'conventional' surgery is then an option and is performed at hospital. A new channel is created for fluid to drain away from the eye, and drops are needed for several weeks afterwards to prevent any swelling or infection. If the new drain in the eye closes up, a second operation is sometimes needed to re-open it again. This type of surgery works better if you have never had eye surgery before. It is always important to remember that the aim of glaucoma surgery is to save sight, not improve it and some people find that although their sight has been saved it is not quite as good as before they had their operation.
What Course Will The Illness Follow?
If untreated or unrecognised, the usual pattern is that the eyesight gradually deteriorates until vision is very poor or blindness occurs. Once treated, regular checks from eye professionals such as opticians and ophthalmologists are vital to make sure the eye pressure is steady and not increasing once more. If the pressure remains the same, the eyesight tends to stay the same also.
Can I Do Anything To Help Myself?
If you are aged over the age of 60, or have a strong family history of glaucoma, or are Afro-Caribbean in race then you should have annual eye checks, even if you are not aware of any eye problems or symptoms.
Tell Your Doctor
1. Do you think your eyesight is getting worse?
2. Can you see things in front of you better than to the side of you?
3. Do you have a family history of glaucoma or eye problems?
4. Have you ever had problems with eye tests in the past?
5. Have you had your glasses changed recently?
Ask Your Doctor
1. What are the side effects of treatment?
2. Am I allowed to drive with glaucoma?
3. What extra risk do my children have of developing glaucoma?
4. Can I go straight to laser surgery without needing to try medication?
5. Does eyestrain make glaucoma worse?
For further information on glaucoma, visit International Glaucoma Association.
By Dr Roger Henderson, MB BS Lond., LMSSA Lond.