Question

What is meant by short-sightedness?

Answer 1

Short-Sightedness (Myopia): A short-sighted eye can see only nearer objects. Distant objects are not seen clearly. In this defect, the image is formed before the retina and far point come closer. This defect can be removed by using a concave lens of suitable focal length. It defected far point is at a distance $d$ from eye then, focal length of used lens $f=-d=-$(detected far point).