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Name: Chris Salmen
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How do glasses help your vision?


Poor vision is the result of an image not being reproduced and interpreted in a true manner when compared with the original object being viewed. There can be neurological problems which interfere with the brain's interpretation of an image....this is not correctable with corrective lenses. The more common cause of poor vision is that a true image reproduction is not made on the retina, the active back inner lining of the eyeball. Because of various ways a persons eyeball might be misshapen, the image entering the pupil of the eye is not accurately focused on the retina. Consider if you are showing slides with a projector with the image sharply in focus. Say at this point someone picks up the projector and moves it closer to the screen without adjusting the focus knob. The image will no longer be in sharp focus. The way to fix this, of course, is to adjust the focus knob.

In the case of the eyeball, sometimes there is a larger-than-normal (from front to back) or smaller than normal (from front to back) condition which makes the image not entirely 'in-focus' on the retina. The way to correct this, PER EYEBALL, is to use a corrective lens to compensate for the misshapen eyeball. The image can then pass through the corrective lens, then the eye's lens, and then through the eye to focus sharply on the retina. Note that each eyeball may have different shape distortions, they might even be 'out-of-round'...this is termed astigmatism and is also correctable with corrective lenses (glasses).


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