Question

Describe the various defects of vision and their corrective measure

Answer 1

hypermetropia : in this eyes cannot see nearby objects .It can be corrected by convex lens
myopia :in this Eyes cannot see distant objects it can be corrected by concave lens
presbyopia: in old ages power of accommodation of Eyes losses therefore the eyes cannot see nearby objects as well as distant objects it can bifocal lensn be corrected by

Answer 2

Defects of the eyes are as follows 
Myopia (Short sightedness) in this type of defect the eye of the person can see nearer object clearly but can't see distant object clearly . 
actually the the image is formed before retina . correction is use concave lens .

Hypermetropia (far sightedness) in this type of defect the person is able to see the distant object clearly but cannot see the near objects clearly . because the image formed is behind the retina . correction is convex lens .

presbyopia - in this defect the person suffer from both myopia and hypermetropia because of gradual weaking of the ciliary muscles and diminishing flexibilty of eye . correction is using bifocal lens .