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GLAUCOMA - THE SILENT BLINDER: Glaucoma is a disease process of the eye whereby the pressure in the eye is abnormally high with resultant damage to the optic nerve of the eye causing a shrinkage of the visual field. If left untreated, blindness will gradually develop. It is one of the most common causes of blindness in the world. It is important to realize that glaucoma is not one disease, but rather a group of diseases. There are different types of glaucoma, the most common being Acute and Chronic, but this answer will be confined to the most common type - Chronic open angle glaucoma. The eye is basically a complex globe filled with fluid. The fluid in the back compartment of the eye is a jelly-like substance and the fluid in the front compartment of the eye is watery. This watery fluid is manufactured by the vascular ciliary body inside the eye and filtered out of the eye, replacing its volume several times a day. If the outflow of this fluid is reduced in any way, glaucoma or high pressure in the eye develops.
This high pressure has a devastating effect on the optic nerve where it enters the eye, and so reduces its ability to conduct visual information from the eye to the brain. Normal pressure of the eye in the general population is between 12 and 19 mm Mercury. The glaucomatous eye has a mean pressure higher than this.
This constant high pressure has the following effects:
1: Initial damage to that part of the nerve conducting visual data from the peripheral part of the retina, causing loss of the patient's peripheral vision. The patient can still see well within his or her central visual field until later in the disease, and usually does not notice the peripheral vision is slowly deteriorating until it is well advanced.
2: Further damage to the nerve causes the visual field loss to progress slowly, until at the end stage of the disease, central vision is also lost.
3: The terminal stage of the disease produces a blind painful eye, which is difficult to treat.
It is important to note that glaucoma can be present in eyes with normal pressure too. This is called "low-tension glaucoma", and is usually accompanied by other signs of degeneration.
A higher than normal pressure can also be present in the eye for short periods without damage to the optic nerve. This is called "ocular hypertension." It is important to note however, that glaucoma often develops in these eyes after a few years.
Question: What are the symptoms of chronic open-angle glaucoma? Answer: Usually none!! Only in the later stages of the disease does the patient complain of loss of vision. It is important to note that it is usually not a painful condition and it can develop without your being aware of it. A small percentage of glaucomas are of the acute type (sometimes called "narrow angle") and can cause severe pain and sudden loss of vision. Seeing halo's around lights is an early warning sign of an impending, acute attack.
Remember, acute, painful glaucoma is a rare disease, whereas chronic, painless glaucoma is very common!
Question: How can glaucoma be detected early? Answer: All people over the age of forty should have their eyes checked for glaucoma by an eye-specialist every two to five years. Measuring of the pressure is especially important in patients who have relatives with the disease.
Question: How is glaucoma treated? Answer: Although the damage to the eye, once caused, can not be reversed, further progression of the disease can be controlled by control of the pressure of the eye. This is done either by means of medical treatment which may include a combination of eye drops or medication by mouth, or if this fails, laser-therapy and surgical procedures can be done to improve the drainage of the fluid of the eye.
It is very important that once you have been diagnosed as having glaucoma, to be followed up regularly by an eye-specialist to monitor the progression of the disease. By doing this, there is no reason why the patient with glaucoma can not lead a normal life without loss of vision, as is inevitable in the untreated patient.
Follow up should include regular monitoring of intra-ocular pressures and measurement of the visual fields to pick up early or progressing damage, and regular examination of the optic nerves.You can use your TV to check your field of vision. A simple test can be performed by sitting about one foot away from the screen with the set tuned to the "snow"-pattern. By first covering the left eye while fixing your central point of vision of the right eye on the middle of the screen, check whether you can see the whole screen out of the corners of your eye, and if you should notice any dark spots, you should consult your ophthalmologist. The test can then be repeated for the other eye
If you have any further questions regarding glaucoma, please consult your eye specialist.