Question

all defect of vision explain it

Answer 1

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

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

✔️ 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.

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

Answer 2

$\Large\underline\mathfrak{Question}$

All defect of vision explain it.

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$\Large\bold\star\underline{\underline\textbf{Hypermetropia\:}}$

Defect

→ In this defect a person cannot see nearby objects clearly but distant objects are clearly visible.

Correction

→ This defect can be corrected by using

suitable convex lens. This defect is also called long sightedness.

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$\Large\bold\star\underline{\underline\textbf{Myopia\:}}$

Defect

→ In this defect a person cannot see distant objects clearly but nearby objects are clearly visible.

Correction

→ This defect can be corrected by using suitable concave lens. This defect is also called near sightedness.

Cause

→ Cause of Myopia: This defect arises due to either ,

1). elongation of the eye ball.

2). excessive curvature of the cornea.

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$\Large\bold\star\underline{\underline\textbf{Astigmatism\:}}$

Defect

→ In this defect a person cannot focus in both horizontal and vertical lines clearly.

Correction

→ This defect can be corrected by using cylindrical lenses. During this rays of light converge as lines instead of converging as points on the retina.

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$\Large\bold\star\underline{\underline\textbf{Presbyopia\:}}$

Defect

→ ) It this defect a person cannot see nearer as well as distant objects clearly.

Cause

→ It is due to weakening of the ciliary muscles and also elasticity of the eye lens decreases.

Correction

→ It can be corrected by bifocal lenses.

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Hope it helped u.

$\huge\bold{\red{\ddot{\smile}}}$