Question

In Section A, defects of the eye are given, in Section B, effects arising due to defects are given and in Section C, remedies are given using lenses. Find the correct pair.

Section A	Section B	Section C
Myopia	Focal length increases	Bifocal lens
Hypermetropia	Focal length decreases	Concave lens
Presbyopia	Power of accommodation decreases	Convex lens

A) (1-y-b), (2-x-c), (3-z-a)
B) (1-z-b), (2-z-b), (3-y-b)
C) (1-x-a), (2-y-c), (3-x-a)
D) (1-y-a), (2-x-a), (3-z-a)

Answer 1

Hint: Before discussing the defects of the eye, we should discuss in brief the normal process of image formation by the eye. When the light rays from an object are incident on the eye, they pass through the pupil and are focused by the lens and the ciliary muscles on the retina. The nerves from the retina conduct electrical impulses to the brain and we perceive the object. Defects of the eye arise when due to some reason the image cannot be focused on the retina or a clear image is not formed. Any number of reasons can cause eye defects but we will discuss some specific cases.

Complete step by step solution:
Near-sightedness (myopia) is a common vision condition in which you can see objects near to you clearly, but objects farther away are blurry. It is caused when the eye lens causes the light rays to bend (refract) incorrectly, focusing images in front of your retina instead of on your retina; it means that the focal length of the eye lens decreases. This defect is corrected by the use of a concave lens which diverges the light rays, causing them to focus at the retina.

Farsightedness, also known as hypermetropia or hyperopia, is an eye defect in which you can see distant objects clearly, but objects nearby may appear blurred. People with severe farsightedness may be able to see only objects a great distance away, while those with mild farsightedness may be able to see closer objects. It occurs when the shape of your eye causes light rays to bend (refract) incorrectly, focusing images behind your retina instead of on your retina; it means that the focal length of the eye lens increases. This defect is corrected by the use of a convex lens which converges the light rays, causing them to focus at the retina.

A condition when a person suffers from myopia as well as from hypermetropia is referred to as presbyopia. A person suffering from this condition cannot distinctly see objects placed at any distance. A person is prescribed a bifocal lens for the correction of this defect.

From the above discussion, we can easily say that option (A) is the correct answer.

Note: Nearsightedness or myopia tends to run in families and can be passed into offspring. You can easily correct this condition with eyeglasses or contact lenses. Another treatment option is surgery. Presbyopia is the loss of the ability to focus on nearby objects. Presbyopia usually becomes noticeable in your early to mid-forties and continues to worsen until around age sixty-five. In the given question, we could have chosen the correct even after knowing the correct matching on any one of the three defects since no two options are the same. For example, the combination of correct matching for myopia is only present in option (A).