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Vision correction

Vision correction

Concave and convex lenses are used for the correction of shortsightedness and farsightedness.

Biology

Keywords

vision correction, short-sighted, farsighted, vision problem, diverging lens, converging lens, dioptre, correction, concave lens, convex lens, lens, glasses, contact lenses, human, biology

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Scenes

Narration

When we look at a nearby object, the lens of the eye becomes curved and a sharp image is formed on the retina.
A shortsighted eye is elongated, its axis is longer than that of a normal eye. Therefore, to form a sharp image, the lens needs to be flatter than in a normal eye.
This is not a problem when we look at a nearby object: the lens becomes less curved as it projects the image onto the retina.

When we look at a distant object, the lens is flat. When the eye is shortsighted, the lens would have to become even flatter to create a sharp image. But there is a point at which the lens cannot become any flatter. Therefore a diverging lens is used to correct our vision.

When we look at a distant object, the lens becomes flat and a sharp image is created on the retina.
The axis of a farsighted eye is shorter than that of a normal eye. Therefore, to form a sharp image, the lens needs to be more curved than it is in a normal eye. This is not a problem when we look at a distant object: the lens becomes less curved as it projects the image onto the retina.

When we look at a nearby object, the lens is curved. When the eye is farsighted, the lens would have to become even more curved to create a sharp image. But there is a point at which the lens cannot become more curved. Therefore a converging lens is used to correct our vision.

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