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How do glasses help your vision?
Name: Chris Salmen
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Age: N/A
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Date: N/A
Question:
How do glasses help your vision?
Replies:
Chris,
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).
Rickru
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Update: June 2012
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