Question

what is longsightedness?

Answer 1

Longsightedness is related to eye sight.In this case, the nearby objects cannot be seen clealr. Whereas the far away objects are clear.

Answer 2

in this case the image is formed behind the retina

Answer 3

Being long sighted means that one can see better farther away than up close. There are three common causes: (1) deformation in the eye, where the person's eye is squished in the front-back direction. Thus, the light that enters the eye is focused behind the retina. (2) deformation in the cornea, where it is too flat and thus the light trajectory is changed. (3) inflexibility in the eye's lens, where it cannot contract enough to focus the light properly on the retina.