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| Glaucoma & Visual Field |
 Glaucoma is the name for a group of diseases that can destroy the optic nerve, the main nerve of the eye. The word glaucoma means "hard eyeball." Any one of the conditions classified as glaucoma can lead to irreversible blindness by damaging the optic nerve.
Glaucoma sneaks up on people. There are no symptoms other than loss of vision, which can occur so gradually that many people do not realize it is happening. The first vision loss is usually peripheral vision (what you can see off to the sides when you are looking straight ahead).
Even though glaucoma cannot be cured, it can be treated. If it is spotted in its early stages, before any sight is lost, blindness can almost always be prevented. But the longer glaucoma remains untreated, the more vision can be lost.
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Glaucoma is considered a thief of eyesight. The only way to make sure that it doesn't sneak up is to have regular eye exams. This is especially true for people with:
- Have a family history of the condition.
- The rate is high with people having darker complexion.
- It is more riskier for people over 40yrs of age.
For reasons still unknown, some people have optic nerves that are more likely to be damaged-usually when fluid pressure in the eye increases. Some experts speculate that these people may have an inadequate blood supply to the optic nerve, or that the tissues supporting the nerve are weak. But no one really knows for sure. In most cases, there is no pain associated with glaucoma and no early warning signs. That is why it is so important to have regular eye exams.
How Glaucoma Progresses?
- The first time many people realize that there might be something wrong with their eyes is when they begin to lose their vision.
- The first to go is peripheral vision, which is what you see on the sides when you look straight ahead.
- Left untreated, glaucoma will eventually lead to tunnel vision, where all a person can see is what is directly in front of the eye.
- From there it can deteriorate to complete blindness.
There are several different types of glaucoma. The most common is called "open-angle" or "chronic simple" glaucoma. It occurs in 80 percent of all people with glaucoma. Other types of glaucoma are:
- Angle-closure glaucoma, of which there are two types: acute angle-closure and chronic angle-closure
- Neovascular glaucoma
- Pigment dispersion and exfoliation glaucoma
- Normal-pressure, or low-pressure, glaucoma
- Infantile glaucoma
Facts About Glaucoma
- More than three million Americans have glaucoma, but half of them don't know it yet.
- Glaucoma damages the optic nerve, which is the bundle of more than 1.2 million different nerve fibers that transmit to the brain what the eye sees.
- Everyone should have a glaucoma check by the time they are 40. They should do so even earlier if they are black or if glaucoma runs in their family.
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| What Causes Glaucoma? |
The eye is filled with aqueous humor and vitreous humor.
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Aqueous humor is a clear fluid in the front part of the eye.
Vitreous humor is a clear, jelly-like substance that fills the eye behind the lens and helps the eyeball keep its shape.
In a normal eye, aqueous humor is produced, circulates through the eye, and then drains out through the trabecular meshwork, which is the eye's filtration system. This is a series of tiny channels near the angle formed by the cornea (the clear portion of the eye), the iris (the colored portion of the eye), and the sclera (the white of the eye).
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If there is any sort of blockage in these channels, pressure builds up inside the eyeball.
Imagine a garden hose with water flowing through it. If you plug the hose, the water pressure builds up. Eventually it will damage the hose.
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Untreated pressure in the eye can damage and eventually destroy the optic nerve, leading to blindness. But, surprisingly, there are some people who suffer from glaucoma even though they have normal pressure in their eyes. There also are people who have pressure in their eyes and yet do not suffer from glaucoma. Researchers are still trying to figure out why.
Somewhere between 20 and 25 percent of people with glaucoma have normal (and maybe even low) eye pressure.
Some people with high eye pressure, which is also called ocular hypertension, do not have glaucoma, and never will. Glaucoma can be hereditary, although having people in your family with glaucoma does not necessarily mean that you will develop it. |
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| What is Visual Field? |
| Visual field is the total area or space in front of us that our eyes are able to see or detect. This area includes both the center portion where we see the clearest as well as the peripheral or outside part that we hardly notice but is also very important while driving, walking, or reading. Have you ever noticed that you turn your head when a car drives out of an alley? This is because your eyes saw the car in the peripheral visual field with subsequent redirection of your attention. |
| Why is the Visual Field so important? |
With a defect in the visual field, one cannot do many of the things in life that we take for granted. One would not be able to drive, read, play, or even walk with the natural ease that we are used to. Most importantly, even if your vision in the current moment is 20/20, your peripheral vision may be damaged if not tested. With the time, this damage will cause complete blindness if not treated. |
| What Can Affect Visual Field? |
| A variety of diseases can damage the visual field. Some examples include glaucoma, strokes, diabetes and cataracts. The most common disease to affect the visual field in a silent manner is glaucoma. Most who have glaucoma are not aware of any symptoms. Unfortunately, glaucoma causes irreversible blindness if not detected and treated on time. |
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