Question

the inability among the elderly to see near objects clearly because of the weakening of the ciliary muscles is called
a far-sightedness
b near sightedness
c presbyopia
d astignation​

Answer 1

Answer:

Presbyopia

Explanation:

1. Presbyopia is a optical disease in the elderly people.

2. In elderly people, the ciliary muscles and the suspensory ligaments become weak and inelastic.

3. As a result, the eye in the elderly people is unable to perform proper "accomodation".

4. Presbyopia is mainly associated with the near point of the eye going away.

In such cases, near point > 25 cm.

5. Usually the far point remains same

(i.e at ∞).

Treatment:

1. Mainly cylindrical lens are prescribed to these people.

2. Even bi - convex lens can be used to correct this vision problem.

Answer 2

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The inability among the elderly to see near objects clearly because of the weakening of the ciliary muscles is called presbyopia.

$\bold{\underline{\underline{\huge{\sf{ExplAination:}}}}}$

• The focusing power of the eye lens decreases with age.

• The muscles near the lens lose their ability to change the focal length of the eye lens.

• The near point of the lens shifts farther from the eye.

• Hence, due to the weakening ability of the muscles near the eyes to change the focal length, elderly people cannot see nearby objects clearly.

SoLuTiOn :

• Sometimes people suffer from nearsightedness as well as farsightedness.

• In such case a bifocal lens is required to correct the defect.

• In such lenses, the upper part is a concave lens and corrects nearsightedness.

• While the lower part is a convex lens which corrects the farsightedness.