Question

Presbyopia corrected by

a. Biconcave lens

b. Biconvex lens

c. Cylindrical lens.

d. It is not need lenses.

Answer 1

presbyopia is the inability of the normal focussing of the near objects with advance of the age - This occurs with advancing age because of hardening of the proteins of lens thus loss of its elastic property - It can also be due to the thickening of the muscle fibres which surrounds the lens Treatment - Can use line free multifocal lenses - which improves the clarity of the vision and helps in the focussing of objects at all distances - Can use bifocal lenses - in which lower part should be convex to focus near object and concave on the upper part for focusing far object - Usually simple convex lens can correct presbyopia

• Bicovex cannot correct presbyopia as they help in focussing near vision but far vision cannot be focused due to loss of elasticity
• Biconcave cannot correct presbyopia as they help in focussing far vision but near vision cannot be focused
• cylinder lens is used to correct faulty vision due to irregular cornea or lens .Here there is no irregularity in the lens
• lens are needed as the focusing is impaired so that simple convex lens is required for focusing the image correctly
• Thus all the options are incorrect. if you has to choose one, you can choose biconvex, but it is tecnically incorrect, because it can cause distorted vision on using, so convex lens are better to use.