Question

What are hypermetropia and myopia ? What is their cause ? How are they rectified ?

Answer 1

$\huge{ \bf{myopia : - }}$

Myopia is also known as $\bf{Near\:Sightedness}$ in which a person is able to see the nearby objects but has difficulty in seeing far objects.

In this defect, the far point of the eye becomes less than infinity. The image of the object doesn't fall on retina and is formed before the retina.

$\textbf{\underline{The causes of myopia are }}$ -:

1) Elongation of the eye ball.
2) Focal length has become small due to increase in curvature of eye lens.

$\textbf{\underline{The correction of myopia is}}$

It can be corrected by using a concave lens (diverging lens) of suitable power that diverges the light rays and the image can be formed on retina.

$\huge{ \bf{hypermetropia}}$

Hypermetropia is also known as $\bf{Far\:Sightedness}$ . It is when a person is able to see far objects clearly but has difficulty in seeing near objects.

In this defect, the Near point of the eyes becomes farther than near point of normal eye, i.e., 25 cm. The image of the object forms behind the retina.

$\textbf{\underline{Causes of hypermetropia}}$ :-

1) eyeball has become too short.
2) Focal length has become longer than 25 cm.

$\textbf{\underline{Correction of hypermetropia}}$:-

It can be corrected by using Convex lens (converging lens) of suitable power that converge the light rays to form image on retina.

$\huge{ \bf{hope \: it \: helps :) }}$

Answer 2

Explanation:

Myopia is known as near sightedness.In this a person can see nearby objects clearly but finds difficult in viewing far distance.In myopia , image is formed before the retina.The causese of myopia are:

i).Elongcation of eye ball.

ii).Focal length has become small due to increase in curvature of eye lens.

It can be corrected by using concave lens.

Hypermetropia is known as far sightedness.In this a person can see far distance clearly but finds difficult in seeing near objects clearly.In this,the image of the

object is formed behind the retina.

The causes of hypermetropia are:

i).Eyeball has become too short.

ii).Focal length has become longer than 25cm.It can be corrected by using convex lens.

Hope it helps you.