Myopia is a defect in human vision where an image of a
- A.nearby object is focused beyond the retina.
- B.nearby object is focused before the retina.
- C.distant object is focused before the retina.
- D.distant object is focused beyond the retina.
Correct answer
Explanation
The correct answer is C, distant object is focused before the retina. In myopia, or short-sightedness, a person sees near objects clearly but distant objects look blurred because their image forms in front of the retina.
Myopia arises when the eyeball is too long from front to back or when the eye lens is too curved and therefore too powerful. Rays from a far object then meet before they reach the retina, and spread out again by the time they fall on it. The far point of such an eye comes closer than infinity. The defect is corrected with a concave, or diverging, lens of suitable power, which spreads the rays a little so that the image moves back onto the retina.
A is wrong because a near object focused beyond the retina describes hypermetropia, or long-sightedness. B is wrong because near objects are seen clearly in myopia. D is wrong because a distant object focused beyond the retina does not describe myopia.
Exam tip: myopia needs a concave lens and hypermetropia needs a convex lens.
Practice Questions
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