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4 Common Eyesight Disorders
Do You Believe That Vision Is Your Most Important Sense? Then You Need To Learn How to Protect Your EyeSight.
By: Bill Coughlin
The hyperopic or farsighted eye is essentially too short (from corneal surface to retina) for the refractive power of the eye. Hence, the light rays from any distant object would theoretically come to a focus behind the retina, which, of course, cant happen because the retina is in the way. If you’ve ever focused a slide-projected picture onto a screen, and then moved the screen closer, the picture is out of focus. That’s the case with Hyeropia eye the retina (screen is too close).
The myopic eye is too long for the refractive power. The light rays come to a focus in front of the retina, and then spread out too form a blurry image. Contrary to the Hyperopic eye, there is no way for the nearsighted eye to clear the image. (Lens focusing would only increase the blur.) Myopic people can see things clearly if they are reasonably close and reading is usually not a problem. Squinting helps a bit in seeing far away because the narrowed opening sharpens the image. Glasses or contact lenses will be prescribed to enable the person to see distant objects.
This is a common disorder, but very difficult to explain. If any of the refractive surfaces of the eye are not symmetrical, parts of the image are clear, parts blurry, looking at a tiny spot of light; the astigmatic eye would see a blurry streak. The culprit is usually the surface of the cornea. Instead of being perfectly round like the surface of a balloon, the cornea is slightly overall as when the balloon is squeezed. Astigmatism causes distortions in the image. You can get the idea by looking into an oval teaspoon and noting the distorted reflection caused by the out of round shape.
“Aging eyes” catches up with most people in their 40s. The first symptoms include difficulty in reading small print, threading a needle, having to hold a newspaper at arms length, etc. For most people, the critical age is 45. Why? To read at 16 inches requires 1-½ diopters of focusing which is just about what the 45-year old has available. Using all of it quickly tires the system. Holding the print at 20 inches reduces the demand to 2 diopters, which can be dealt with for a short reading session. Holding the print still further, say 26 inches, can get you by for a longer time since only about 1-½ diopters are needed.
Farsighted people are affected at an earlier age because they use up some of the focusing for far seeing. A succinct description of Presbyopia would be:
The brain is willing but the lens is not fully responsive and your arms are too short. This is, the brain continues to send signals to the lens to accommodate, but the lens cannot comply as it did when it was younger.
While it is possible for both eyes to have the same refractive condition, it seldom happens, although they’re usually similar. Learn more at http://www.protect-
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What we feed our bodies feeds our eyes. Many of the vitamins and minerals in our bodies are found in much higher concentrations in our eyes, so a diet lacking in these vitamins and minerals can lead to vision problems as we grow older.