Glaucoma Causes and Treatment
The eye is filled with a clear fluid (called aqueous humor) that has the consistency of half-set jelly. This fluid is slowly secreted by special cells within the eye, while in another part of the eye, the fluid is slowly removed, causing a steady renewal of the eye's contents. This exchange occurs quite slowly, but when it is disrupted, glaucoma occurs.
The fluid is produced by a structure called the ciliary body which sits just behind the iris (the colored part of the eye). The fluid moves through the pupil (the black hole in the center of the iris), and is drained back into the body through tiny canals that are situated around the outer edge and in front of the iris. The usual disruption to this circulation of the eye contents involves a blockage to the drainage of the fluid from the eye. The new fluid continues to be secreted, and as a result the pressure inside the eye increases. With this increase in pressure, damage occurs to the light-sensitive areas at the back of the eye, eventually causing them to be permanently scarred, and blindness results.
Glaucoma is diagnosed in most cases by measuring the actual pressure of the fluid within the eye. This involves briefly anesthetizing the eye surface with eye drops, and then resting an instrument called a tonometer on the surface of the eye while the patient is lying down. The procedure takes only a few seconds and involves no discomfort. Other more complex tests, including examining the eye through a microscope, are undertaken by eye specialists to ascertain the nature and seriousness of the glaucoma.
Measurement of the damage to the field of vision may also be undertaken by asking a patient to stare at a black dot in the center of a large white sheet. Another black dot is then moved in from the side of the white area until it can be seen by the patient. The sideways limit of vision can then be marked on the sheet, and the procedure is repeated from different angles so that the field of vision can be mapped out in all directions.
Glaucoma occurs in three main types.
Chronic glaucoma (also known as open-angle glaucoma) is by far the most common type. It has a slow onset over months or years and is usually detected because of a deterioration in vision. This type of glaucoma tends to occur in both eyes simultaneously and also runs through families from one generation to the next. Anyone over 40 with glaucoma in the family should have the pressure in their eyes tested every couple of years to detect the onset of glaucoma before it causes any damage. Patients with diabetes and arteriosclerosis (hardening of the arteries) are also more liable to develop this form of glaucoma.
Acute glaucoma (also called angle-closure glaucoma) is the worst type, as it can develop in a few hours or days. It usually occurs in only one eye, and blindness can result if medical attention is not sought urgently. The symptoms include a rapid deterioration in vision, severe pain, rainbow-colored halos around lights, nausea and vomiting. A blow to the eye may precipitate acute glaucoma, or it may develop for no discernible reason. Immediate treatment is essential if the sight of the eye is to be saved.
The alternative names for these two types of glaucoma refer to the angle between the iris and cornea, at which point the fluid in the eye is normally resorbed back into the body.
Babies born with this disease require surgical treatment to give them some chance of retaining their sight. The earliest sign of this condition is the continual overflow of tears from the eye. It may also be noted that the baby turns away from lights, rather than towards them as a normal baby does.
A number of other conditions may also cause glaucoma. These include eye tumors, eye infections and eye injury. In rare cases, some drugs (e.g. steroids) may also be responsible.
Both the acute and chronic types of glaucoma can be treated medically in the majority of cases. This involves the regular use of eye drops that are designed to reduce the pressure in the eye. These drops do not cure the disease but keep it under control while they are used. If the eye drops are not successful, or the situation is very serious, microsurgery on the tiny drainage canals in the front of the eye may be necessary. Lasers are being used in some centers for this procedure. The surgery may cure the disease, but usually it merely brings the pressure in the eye to a level where the drops are able to work.
Without treatment, glaucoma progresses inexorably to total blindness. If the disease is detected early, glaucoma in most patients can be successfully controlled.
Blindness is a terrifying affliction, but blindness that could have been avoided if adequate treatment had been sought is even worse. If you notice a deterioration in your sight, particularly if it is accompanied by eye pain or headaches, see your doctor immediately, so that the appropriate diagnosis can be made at an early stage of the disease.
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