How do glasses correct vision? Detailed answer

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How do glasses correct vision? Detailed answer

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How do glasses correct vision?

It is impossible to even imagine that the life of millions of people can be complete without glasses! If you are nearsighted, you will not be able to see the night stars. You will not be able to see clouds, distant mountains, or a bird flying high above. Thanks to vision correction, people with nearsightedness can now see just as well as people with normal vision. We see because the light entering the eye falls on the retina of the eye, as on the sensitive plate of a camera. It is clear that if the light falls on the retina or in front of it, then we are not able to see clearly.

The eye has a lens to focus the light and direct the rays to the desired point. When normal eyes look at a distant object, the image hits the retina without problems. But when the same eye looks at a close object (say, closer than five meters), the image is focused behind the retina. The lenses of the eyes "accommodate". This means that the right muscles contract and change the shape of the lens. This directs the image to the retina and the eye sees the object clearly.

Two things can make accommodation impossible. The first is when the lenses of the eyes age and lose their elasticity. The lenses cannot change shape and focus the image. The second reason is that people are born with eyes that are too long or too short. People with too short eyes are farsighted. They see distant objects well, but must strain their eyes a lot when looking at close objects.

Sometimes it is not possible to do this well enough to bring the image into focus on the retina. These people need glasses. Glasses do work that the muscles of the eye cannot do. They focus the image on the retina without accommodation of the eye.

Nearsighted people have very long eyes. The image is focused in front of the retina and blurred. But short-sighted people can't do anything about it. If they accommodate the eye by tensing the muscles of the eye, then they can only move the image forward. They need glasses that shift the focus back to the retina so they can see clearly.

Author: Likum A.

Random interesting fact from the Great Encyclopedia:

What is the meaning of the alternation of color and black and white scenes in the film Uncle Vanya?

In the film directed by Andrei Mikhalkov-Konchalovsky "Uncle Vanya", released in 1970, there are both color and black-and-white scenes. Some critics have found artistic justification for this technique. In fact, there were not enough stocks of color Kodak, and Soviet color film did not give the desired image quality, which is why they shot in black and white.

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