Question

Lens is used to correct the defect of vision termed as presbyopia.
A. Convex
B. Concave
C. Bifocal
D. Contact

Answer 1

Hint: Recall the different defects of vision in the human eye and the types of lenses used to correct these defects of vision. Recall the basics of the defect of vision termed as presbyopia. Also, check which types of lens are used to correct this defect of vision of the human eye.

Complete answer:
The person with the defect of vision myopia is the defect in which the person is not able to see the objects at large distances clearly is known as myopia. This defect of vision can be corrected using a concave lens.

The person with the defect of vision hypermetropia is the defect in which the person is not able to see the objects at near distances clearly is known as hypermetropia. This defect of vision can be corrected using a convex lens.

The defect of vision termed as presbyopia is the defect mostly occurring in old-aged persons in which the persons lose their ability to see the distance as well as nearby objects. This defect of vision includes two defects of vision which are myopia and hypermetropia. Hence, the person with the defect of vision presbyopia is suggested to use the lens having both concave and convex lenses.

The bifocal lens is made of concave as well as convex lens. The upper part of this bifocal lens is made up of the concave lens and lower part of this lens is made up of convex lens. Hence, the person with presbyopia can see near as well as distant objects clearly. Therefore, the lens used to correct the presbyopia of the person is bifocal.

Hence, the correct option is C.

Note:The presbyopia can also be defined as the defect of vision due to aging in which the person cannot see the nearby objects clearly. Hence, a convex lens is suggested for such persons. But the person cannot see distant objects clearly using this lens. Hence, to avoid frequent wearing and removing of the spectacles, persons with presbyopia are suggested to use bifocal lenses.