Question

explain the defects of vision and correction of with neat diagrams

Answer 1

Defects of Vision and their Correction
Sometimes the eye may gradually lose its power of accommodation and the person cannot see the objects clearly and comfortably. This happens because of refractive defects of the eye because of losing of power of accommodation of lens.

There are mainly three types of defects of vision these are Myopia, Hypermetropia and Presbyopia.

Myopia or Near Sightedness or Short Sightedness
Myopia is known as Near Sightedness or Short Sightedness also. A person suffering from myopia can see objects placed nearby clearly but cannot see the objects placed at a distance clearly.

Correction of Mypoia Near Sightedness or Short Sightedness
Mypoia or Near Sightedness or Short Sightedness can be corrected by using a diverging lens (Concave lens) of suitable power. Converging lens diverge rays of light coming from the object and object appears placed farther than actual place. This makes image at retina which enables a person having Myopic eye defect see clearly.
Hypermetropia or Far Sightedness
Hypermetropia is known as Far Sightedness also. A person's eye suffering from Hypermetropia can see an object placed at a distance but cannot see that placed at nearby clearly. He sees object placed at nearly blurred.
Correction of Hypermetropia or Far Sightedness
This defect can be corrected using a converging lens (Convex lens) of appropriate power. Converging lens converse the light rays coming from object and object appear placed at more distance than normal. Because converging of light rays coming from object image formed at retina and person suffering from this defect sees the object clearly.

Presbyopia
Person suffering from presbyopia find it difficult to see the objects placed nearby comfortably and distinctly.
Correction of the eye defect of Presbyopia
The defect of Presbyopia is corrected by using a converging lens (Convex lens). Convex lens converge light rays coming from object placed nearby and object appears slightly far from the actual place and image formed at retina. After correction person suffering from Presbyopia can see the object clearly.

Answer 2

$\large\bf{\underline{Here\: is\: your \:answer:-}}$

$\sf{\underline{The\: main\: defects \:of\: vision\:are:-}}$

✔️ Myopia.
✔️ Hypermetropia.
✔️ Presbyopia.

$\bf{\large{Myopia}}$

Myopia is also known as near-sightedness. A person with Myopia can see nearby objects clearly but cannot see distant objects distinctly.

This defect arises due to :-
⏩ Excessive curvature of the eye lens.
⏩ Elongation of the eyeball.

This defect can be corrected by using a concave lens of suitable power.

$\bf{\large{Hypermetropia}}$

Hypermetropia is also known as far-sightedness. A person with hypermetropia can see distant objects clearly but cannot see near by object distinctly.

This defect arises due to:-
⏩ The focal length of the eye lens is too long.
⏩ The eyeball has become too small.

This defect can be corrected by using a convex lens of appropriate power.

$\bf{\large{Presbyopia}}$

The power of accommodation of eyes usually decreases with ageing. They find it difficult to see nearby objects comfortably and distinctly without corrective eye-glasses. This defect is called Presbyopia.

This defect arises due to:-
⏩ Gradual weakening of ciliary muscles.
⏩ Diminishing flexibility of the eye lens.

This defect can corrected by using bi-focal lenses consists of both concave and convex lenses.

$\huge\mathfrak\red{Hope\:it \:helps\: you}$