Refraction (Patience please. A lot of stuff is being loaded)




When looking at an object that is far away the lens is kind of skinny. To see what happens when looking at a nearby object select continue.

(You can get a better idea of the change in lens shape by repeated selecting "continue" and "back" to alternate between graphic displays.)




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When looking at nearby objects the lens gets fatter, causing the image of the object to be focused on to the retina in the fovea.

To see what would happen if the lens did not get fatter select continue.

By the way, the technical term for this change in lens shape is accommodation. We frequently call it focusing.






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If the lens can not properly focus light on the retina, the image will fall either behind or in front of the retina.

Can you guess what would happen if the lens is too fat?

Select continue to find out.

Select demo picture to see what a scene under these conditions might look like

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If you guessed that when the lens is too fat that light is focussed in front of the retina, you were right.

Is there a remedy for lens problems that do not allow light to be properly focused on the retina? Sure, select continue.

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Many people wear contact lenses to help image light properly on to the retina. Another solution is for a person to wear glasses. This places a lens in front of the eye not on the cornea as is the case with contact lenses.

A recent solution is to use a laser to reshape the cornea. this solution is possible only in some cases.

Another optical problem is astigmatism.



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