Back to  How do your eyes work?
How come your eyes go big in the dark and little in the light?
Why do we have different coloured eyes?
If the light reflects off the cornea and you see upside down and your brain flips the picture, how can we feel them right side up?

We got several scientists to answer this question including Thèrèse Mercier, and Pierre Kerr, ac210@freenet/

Your eyes provide you with one of the most important senses, sight.

This diagram show the parts of the eye. Light travels through the cornea, which is clear, and passes through the iris. The iris controls how much light goes into your eye. If it's very bright, the iris closes and if it's dark it opens.

The iris is also the part that gives your eye the colour. Brown eyes have a brown iris. The colour is something that you inherit from your parents and has nothing to do with the function of your eye.

The lens is held by muscles that can bend it to provide different focusing. For seeing things far away, the muscles relax and let the lens flatten. For seeing something close, the muscles squeeze the lens to make it fatter.

An image that goes through the lens is turned upside down and reflects on the back of the eye, the retina. The retina is a soft, transparent layer of nervous tissue made up of millions of light receptors. The retina is connected to the brain by the optic nerve.

The brain takes these signals and interprets them as an image, right side up. Your brain is a very versatile organ and is able to do things like this without you having to think about it. Experiments have been made where a person is fitted with glasses that turn what they see upside-down so as they walk around everything would seem wrong-side up. After a while, they are able to function fine. They're brains adjust to the mixed up image.

Your school library has good books that describe how many things work including eyes. Take a look at:


"You Won't believe your eyes'

Nancy Crystal & Milan Tytla

- optical tricks plus an explanation of how your eyes work

Thanks for your questions and have a good summer.

Answer #% % filename Document2 page% % page 1 of% % numpages 1 % % date \@ "MMMM d, yyyy"June 18, 1995


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