Question

what is myopia, hypermetropia, cataract, presbyopia?

=> Write theirs reason of defects and correction for them ?​

Answer 1

Explanation:

Presbyopia is that defect of vision due to which an old person cannot see the nearby objects clearly due to loss of power of accommodation of the eye. ... It is possible to correct the refractive defects of the eye (such as myopia and hypermetropia) by using contact lenses or by undergoing surgical procedures

plz mark me brainliest answer very soon urgent

Answer 2

$\underline{\bigstar{\pmb{\sf{\blue{Myopia \;(\;Near\; sightedness\;) :}}}}}$

$\red\dag$Reason of the defect :

• ➮ Excessive curvature of eye lens that is eye lens becomes thick and its focal length decreases.
• ➮ Elongation of the eye ball.

$\footnotesize\bf{\red{\dag}\:\underline{\pink{\frak{Correction :}}}}$

• ➮ This defect is corrected by using concave lens of suitable power.

$\rule{200}2$

$\;\;$

$\underline{\bigstar{\pmb{\sf{\green{Hypermetropia\; (\;Far\; sightedness\;)\;:}}}}}$

$\pink\dag$Reason of Defect :

• ↠Increase in focal length of the eye lens.
• ↠ Eye ball has become too small.

$\footnotesize\bf{\pink{\dag}\:\underline{\orange{\frak{Correction\;:}}}}$

• ↠ Corrected by using convex lens of suitable power.

$\rule{200}2$

$\;\;$

$\underline{\maltese{\pmb{\sf{\purple{Presbyopia\;:}}}}}$

• » Gradual weakening of ciliary muscles, thereby decreasing the flexibility of the eye lens.

$\footnotesize\bf{\green{\dag}\:\underline{\blue{\frak{Correction\;:}}}}$

• » Using Bifocal lens with appropriate power.

$\rule{200}2$

$\;\;$

$\underline{\maltese{\pmb{\sf{\red{Cataract\;:}}}}}$

• ➪ The image cannot be seen distinctly because eye lens become milky and cloudy.
• ➪ This condition is known as cataract, it can cause complete or partial loss of vision. This can be corrected by surgical removal of extra growth (cataract surgery).

$\;\;$

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━