Glaucoma damages the optic nerve, the nerve of sight, causing blind spots in areas of vision. People rarely notice these blind areas in the side vision until considerable optic nerve damage has occurred or the blind areas are very large in late onset. Usually people notice this damage when visual field is narrowed.
Causes
Normally, an aqueous humor-a clear transparent liquid- flows through the inner eye continuously. If the drainpipe is blocked, the fluid pressure within the inner eye is increased and leads to damage to the optic nerve. Hence, the field of vision is also damaged and becomes narrow.

There are 4 forms of glaucoma

1. Chronic open-angle glaucoma
This type accounts for the majority of glaucoma in most countries. It affects mainly the elderly but can also affect the middle-aged. Members of the family or relatives of people with glaucoma have a higher risk of having the disease as there is usually a hereditary factor involved.
Glaucoma progresses slowly and often goes unnoticed for many months or years. Many people are unaware that their eyesight is deteriorating as a person's straight ahead vision and reading vision remains good initially, but there is a gradual loss of night vision and side vision. The best way to diagnose is by means of a medical eye examination.

2. Acute angle-closure glaucoma
The iris may press up against the drainage area and close it off. This action increases eye pressure rapidly and leads to complete blockage of fluid flowing out of the eye. If not treated immediately, it can result in permanent damage to the eye in a few days. Acute glaucoma often has very marked symptoms such as severe pain in the eye, blurred vision, redness, the appearance of haloes around lights, and vomiting.

3. Congenital glaucoma
This type of defect is abnormal from birth. Since an infant's eye has more elasticity than an adult's, when pressure inside the eye is increased, the simply stretchable eye may enlarge. Hence, the front of the eye is blur like fog on a windshield.


4. Secondary glaucoma
Other conditions such as injuries, certain drugs, hemorrhages, tumors, and inflammations can sometimes block outflow channels in the eye.

Risk takers
A history of glaucoma in the family, diabetes, hardening of the arteries, or anemia is the example of risk factors.

Treatment

The earlier the condition is diagnosed, the greater the chances of success in preventing vision loss. Although glaucoma cannot be cured, in most cases it can be successfully controlled. The type of therapy depends on the form of glaucoma and may be administered by medication-eye drops, tablets-, surgery or laser therapy.
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