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Q & A: Seeing the Distance

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Most recent answer: 10/22/2007
Q:
What is long/short sight. How is it treated and what do the opticians do to correct it?
- loulabelle (age 14)
northants
A:
Let's start with the human eye. Light enters the eye and gets focused onto the retina in the back. The retina changes the light into a signal the the brain reads and interprets into the image we "see". In front if the eye is a lens. Like the lenses you see in people's glasses, this helps bend the light.

What makes the lens in our eye even more special is that it is flexible. There are some muscles in the eye that stretch and compress the lens to change its strength. Much like how a camera moves 1 of its 2 main lenses to focus an image, our lens changes shape to focus an image.

The lens doesn't always work perfectly. It can get tougher and won't change shape exactly like it should. That makes it hard to see certain distances clearly. Depending on the way your lens is stuck, you might see far things better than near (far-sighted) or you may see near by things better (near-sighted). Then, if you look at some things, you lens can't focus the light properly and the image looks fuzzy.

An optometrist fixes this by putting another lens in front of your eye. This bends the light the rest of the way that your own lens no longer can. Your lens will still adjust itself to keep things in focus, but now you can see everything correctly.


Adam

(published on 10/22/2007)

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