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Asked by emmagrace to Dalya, Derek, Sarah, Tim, Tom on 21 Jun 2011.
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Tim Millar answered on 20 Jun 2011:
Glasss help to focus light onto the back of the eye where it can be detected and sends information off to the brain. If the eye ball is too short or too long, the lense will focus the light into the wrong place. Glasses help to bend the light enough to allow this focussing onto the retina.
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Sarah Thomas answered on 20 Jun 2011:
Yes glasses help focus light in the way that Tim described but wearing glasses does not improve your eye sight, because when you take them off, your vision is terrible again.
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Derek McKay-Bukowski answered on 20 Jun 2011:
Good answers Tim and Sarah!
(And yes, Sarah is quite right… glasses don’t improve your eyesight permanently — only while you’re wearing them!)
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Tom Crick answered on 21 Jun 2011:
Corrective lenses (glasses or contact lenses) are used to treat defects in vision: myopia (shortsightedness — I have this!), hyperopia (longsightedness), astigmatism (irregular curvature of the eye — my brother has this!) and presbyopia (where your eyesight degrades with age).
The different types of lenses help focus light onto the back of the eye (the retina): myopia requires a divergent lens (spreads the light out), whereas hyperopia requires convergent lens (focuses the light).
Comments
emmagrace commented on :
So will you be blind, tim if you didnt wear your glasses?
Tim commented on :
No, just not as able to see as well, we can all compensate for some degree by using the muscles around the lense in the eye. As we get older, the lense becomes less elastic so this is harder to do, so eventually we will all need help with seeing clearly
emmagrace commented on :
You now im short sighted why is this? i dont think i was short sighted before
🙁
Tim commented on :
There maybe a couple of reasons for the short sightedness. Its possible that your eyeball is too long so that the light is focused by the lense to early in the eye. Your glasses would then help to move the focal point back a little until it lands on the retina. There may also be a difference in your mucslces surrounding the lense that they are not strong enough to streth the lense to focus the light further back in the eye.
emmagrace commented on :
How long have you been in im a scientist?