Question

explain about myopia,hyper metropia and press biopia ...... don't copy

Answer 1

myopia is in which close objects appear clearly, but far ones don't.

hyper metropia is when person is not able to see close objects clearly

Answer 2

MYOPIA :
it is also known as short -sightedness .
in this defect of vision a person cannot see the distant object clearly but can see nearby objects clearly . In amyopic eye the image of the object is formed in front of the retina . this defect is caused due to :
1. increase in the curvature of the eye lens .
2. increase in the size of the eye ball.
it can be corrected by using concave lens of suitable power.

HYPERMETROPIA:
it is also known as long -sightedness . in this defect of vision a person can see the distant object but cannot see the nearby object . the image is formed behind the retina . it us caused due to :
1.increase in the focal length of the eye lens .
2. decrease in the size of the eye ball.
it can be corrected by using convex lens of suitable power.

PRESBYOPIA:
this defect of vision is usually caused in the old age . in this the person cannot see the nearby objects distinctly without corrective eye glasses. it arises due to :
1. weakening of the ciliary muscles
2. diminishing flexibility of the eye lens ....