MCQ Detailed View

Short-sightedness, also known as myopia, is a common vision defect in which a person can clearly see nearby objects but distant objects appear blurred. This condition occurs because the eye’s lens focuses incoming light rays in front of the retina instead of directly on it. The main cause of myopia is either the eyeball being too long or the cornea having too much curvature, causing excessive bending (refraction) of light.

To correct short-sightedness, concave lenses (diverging lenses) are used in spectacles or contact lenses. A concave lens is thinner at the center and thicker at the edges. When light rays from a distant object pass through a concave lens, the lens diverges (spreads out) the rays slightly before they enter the eye. This adjustment makes the eye’s natural lens focus the image directly on the retina, allowing clear vision of faraway objects.

Other options are not correct:

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  Convex lens: Used to correct long-sightedness (hypermetropia), where light focuses behind the retina.

  
  


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  Convex-concave lens: This is a compound lens not typically used for myopia correction.

  
  


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  Concave-convex lens: Similarly, not the standard solution for myopia.

  
  

The physics principle behind this correction is based on refraction of light. Concave lenses change the path of incoming light rays, reducing their convergence so that the focal point moves backward onto the retina. The power of the concave lens (measured in diopters) depends on the severity of the myopia and is prescribed after an eye examination.

In conclusion, short-sightedness (myopia) is corrected by using concave lenses, which diverge light rays and help the eye form a clear image on the retina, restoring normal vision.