• Question: How can glasses improve someones eyesight?

    Asked by emmagrace to Dalya, Derek, Sarah, Tim, Tom on 21 Jun 2011.
    • Photo: Tim Millar

      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.

    • Photo: Sarah Thomas

      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.

    • Photo: Derek McKay-Bukowski

      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!)

    • Photo: Tom Crick

      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).