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प्रश्न
Distinguish between:
Myopia - Presbyopia
उत्तर
| Myopia | Presbyopia | |
| 1. | This problem of vision arises due to slight elongation of eyeball or curved lens. | In this problem, the near point of aged people recedes. Also, ciliary muscles lose the capacity to change the focal length ofthe eye lens. |
| 2. | In this defect, human eye can see nearby objects distinctly but unable to see distant objects clearly. | In this defect, aged people find it difficult to see nearby objects comfortably and clearly. Sometimes they are unable to see nearby as well as distant objects clearly. |
| 3. | This defect can be corrected using concave lens of suitable focal length. | This defect can be corrected using bifocal lens in which concave lens is useful for distinct vision and convex lens is useful for near vision. |
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संबंधित प्रश्न
A person needs a lens of power -5.5 dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power +1.5 dioptre. What is the focal length of the lens required for correcting (i) distant vision and (ii) near vision?
Anuja’s father cannot see nearby objects clearly.
(a) What is the eye defect he is suffering from?
(b) How is it corrected?
Bifocal lens is required to correct _______ defect.
Write the name.
The defect of eye occurring due to ageing
Write scientific reason.
Presbyopia effect is more common in people over 40 years of age.
The eye defect ‘presbyopia’ can be corrected by
Complete the correlation:
Farsightedness : Convex lens : : Presbyopia : ______
Write a short note on Presbyopia.
