To keep it light-weight for rapid movement, the eye is made from soft, but strong tissues. However, like a camera, the eye needs to maintain its shape so that it can focus light accurately. This is achieved by keeping the eye firm, like a balloon. Clear fluid (the aqueous) is pumped into the eye from the bloodstream carrying oxygen, sugars and other essential nutrients. Circulating around the structures inside the eye, the aqueous is then drained through a meshwork back to the blood to be renewed. Drainage is against resistance, so the eye's pressure is kept higher than air pressure, but lower than the blood pressure.
Glaucoma is the name given to a group of eye diseases in which the optic nerve at the back of the eye is slowly destroyed. In most people this damage is due to an increased pressure inside the eye - a result of blockage of the circulation of aqueous, or its drainage. In other patients 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. Over 300,000 Australians have glaucoma. While it is more common as people age, it can occur at any age. As our population becomes older, the proportion of glaucoma patients is increasing.
For more information or to make a donation go to glaucoma.org
Courtesy of glaucoma.org
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David Shanahan © 2009