Question

Bi focal lens is used to correct:
A. Cataract
B. Astigmatism
C. Myopia
D. Presbyopia

Answer 1

Hint: Bi focal lens consists of both convex and concave lens. It consists of two distinct optical powers. Optical power refers to the degree of the lens at which light diverges or converges. If a person has eye problems where he can’t see both too far and too near objects, he can use these lenses so that each lens can be used for each deficiency.

Complete answer:
Bi focal lens is commonly prescribed to people suffering with presbyopia. Presbyopia is a disease that usually occurs at old age due to weakening of nerves that focus on the objects that we see. As we age, the ability to focus on things worsen and thus, bi focal lens is used to correct the focus. These lenses help in focusing things that are too near and also too far as both lenses are used in this lens.

Therefore, the correct option is option d.

Additional information:
Symptoms for presbyopia disease can be difficulty in reading papers and stuff at low light conditions. Our eyes get strained when we read or watch things for long periods of time. If we change the viewing distance suddenly, the eye gets blurred as it takes time for the eye to focus on things.

Note:
There are ways to correct the presbyopia effect using laser treatment and contact lens. Laser treatment rarely has advantages but is associated with a lot of risks. This disease affects almost everyone when they age. It also affects people who are already suffering with myopia or hypermetropia.