Question

in which defect do we use cylindrical lenses for its correction​

Answer 1

Answer:

The eye defect, astigmatism can be corrected by using a spherical cylindrical lens.

Those who suffer from astigmatism cannot see objects clearly, when the light from certain parts falls on the retina and the rest falls on either behind the retina or in front of it. This is caused by the irregular curvature of the cornea.

Since the problem is that the cornea or the eye lens are not symmetrical, the solution is to use eye glasses whose lenses are not symmetrical in a complementary way. An extreme version of this is a cylinder lens – a shape that is circular in one direction where it acts as a normal lens and flat in the other direction where it has no focusing properties. The strength and direction of the cylinder are designed to compensate for the asymmetry of the cornea or the eye lens. The curved portion of the cylinder lens may be positive or negative, depending on the detailed asymmetry in the eye.

Hope this helps $\mathtt{: )}$

Answer 2

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Explanation:

The eye defect, astigmatism can be corrected by using a spherical cylindrical lens.

Those who suffer from astigmatism cannot see objects clearly, when the light from certain parts falls on the retina and the rest falls on either behind the retina or in front of it. This is caused by the irregular curvature of the cornea.

Since the problem is that the cornea or the eye lens are not symmetrical, the solution is to use eye glasses whose lenses are not symmetrical in a complementary way. An extreme version of this is a cylinder lens – a shape that is circular in one direction where it acts as a normal lens and flat in the other direction where it has no focusing properties. The strength and direction of the cylinder are designed to compensate for the asymmetry of the cornea or the eye lens. The curved portion of the cylinder lens may be positive or negative, depending on the detailed asymmetry in the eye.

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