Question

Explain any two defects of vision

Answer 1

Here is ur Answer .

MYOPIA or NEARSHIGHTED. Myopia occurs when the eyeball is too long, relative to the focusing power of the cornea and lens of the eye.

HYPEROPIA or FARESIGHTED. This vision problem occurs when light rays entering the eye focus behind the retina, rather than directly on it. 

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.

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