March17 1Glaucoma is the name given to a group of eye diseases in which the optic nerve at the back of the eye is slowly destroyed, usually due to increased pressure in the eye, although it may occur with normal eye pressure. In some cases, the damage may be caused by poor blood supply to the vital optic nerve fibres, a weakness in the structure of the nerve, and/or a problem in the health of the nerve fibres themselves.

Glaucoma is one of the leading causes of blindness in the world. Worldwide about 66 million people are affected with glaucoma. About 10 % of these become blind due to glaucoma. In South Africa it is estimated that about 200,000 people are affected.

The shape of the eye is achieved through the circulation of a clear fluid (aqueous), which bathes and nourishes the eye, keeps it firm and gives the eye a certain pressure. High pressure left uncontrolled can lead to damage of the optic nerve and result in vision loss. Eye pressure varies from person to person - what is high pressure for one person may not be for another.

Glaucoma is referred to as the “silent thief of sight” because it is a largely invisible disease of the eyes, and there are usually no symptoms, so it often goes undiagnosed until late in its progression.

Glaucoma can present at any age, although the commonest type, primary open angle glaucoma occurs after the age of 40 years. Although rare, one can be born with glaucoma! The earlier the onset of glaucoma, the more aggressive it is and the more damage will occur sooner.

Males and females are affected equally.

Usually both eyes are affected, although one eye may be more advanced.

Although anyone can develop glaucoma, some people have a higher risk. If there is a family history of glaucoma, the chances of developing glaucoma sooner is higher. Other risk factors include a high degree of shortsightedness, a high degree of farsightedness, diabetes, a history of migraine, trauma to the eye (even if not recently), and ocular inflammation. Glaucoma is not associated with high blood pressure.

March17 2Those who have chronic glaucoma may not be aware of any symptoms because the disease develops slowly and loss of peripheral vision is rarely noticed until there is already damage. The damage is progressive and irreversible. But if diagnosed early, glaucoma can be controlled and further vision loss can be prevented. Ocular pressure should be regularly checked by your optometrist.

Those who have an acute form of glaucoma may develop severe symptoms because ocular pressure rises quickly. They may experience sudden severe pain in one eye affecting the whole side of the head, partial loss of vision, blurred vision, especially at night, halos or rainbows around lights, severe headaches, or nausea.

March17 3There are various techniques as part of a routine eye examination to detect glaucoma, ranging from puff tonometry (where a small puff of air blows against the cornea) to applanation tonometry (where local anaesthetic is used and the instrument softly and gently touches the cornea). A visual field test may be done to measure the degree of glaucoma damage and examinations may be done to evaluate the degree of damage to the optic nerve.

The aims of glaucoma treatment are to decrease intraocular pressure and prevent further damage to the optic nerve. Treatment cannot recover what has been lost, but it can arrest, or at least, slow down the damage process. That is why it is so important to detect the problem as early as possible. Treatment options include eye drops, laser treatment to open the drainage angle and reduce pressure, and surgery to create a new pathway for fluid drainage.

Don’t wait for deteriorating vision to go for a glaucoma screening, by which time there may already be significant loss of peripheral vision. Visit your optometrist sooner rather than later for a quick and painless glaucoma screening

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