Question

Astigmatism is corrected by the use of
A. Convex lens
B. Concave lens
C. cylindrical lens
D. Surgery

Answer 1

Astigmatism is a type of refractive error in which the eye does not focus light evenly on the retina, and astigmatism results in a blurred or distorted vision at any distance, or her symptoms which caused due to astigmatism include eyestrain, headache, etc. If this astigmatism condition occurs in early life then it is termed as amblyopia.

Complete answer:
The reason for astigmatism is unclear, but it is believed to appear because of genetic factors.
Astigmatism can occur in children and as well as in adults, but the risk is more if there is any family history of astigmatism.
This condition generally causes the thinning or scarring of the cornea.
Astigmatism is of different types, and it is classified based on the focus of the principal meridian. They are
Simple hyperopic Astigmatism: in this type, the 1st focal line is on the retina, and the 2nd focal line is located behind the retina.
Simple myopic Astigmatism: In this type, the 1st focal line is in the front of the retina, while the 2nd focal line is on the retina.
Compound Astigmatism: This is also divided into two types, which include:
Compound hyperopic Astigmatism: Where both focal lines are located behind the retina.
Compound myopic Astigmatism: Where both focal lines are located in front of the retina.
Mixed Astigmatism: Focal lines are on both sides of the retina.
Diagnosis: Various tests are used during an eye examination to determine the presence of Astigmatism, and they use a keratometer, which is used to measure the front surface of the cornea, and also an autorefractor, which is used to identify the eyes refractive error.
Treatment options: Astigmatism is corrected by eyeglasses, contact lenses, and the lenses used for the correction are spherical or cylindrical lenses are preferred, and in some cases, refractive surgery is the treatment option.

Note: To say briefly, any changes or distortion in the shape of the cornea, results in improper focus of light that results in a condition called astigmatism, and it is treated by using glasses, lenses, and sometimes by surgery.