Question

State the defects of vision in human eyes and its remedies. Explain the defect of myopia and remedies to control it.

Answer 1

The inability of the ciliary muscles to change the thickness of eye-lens as per requirement and to form the image of an object on the retina leads to the defect of vision.

The three main common defects of vision are as follows:

• Myopia or near-sightedness (Corrected by concave lens)
  
• Hypermetropia or far-sightedness (Corrected by convex lens)
  
• Presbyopia (Corrected by bifocal lens)

Myopia or near-sightedness: It is the inability of the eyes to see distant objects clearly. It arises when the eye-lens does not become thin as per requirement and as such the image of the object is formed at a distance shorter than the retina. Myopia can be corrected by using a concave lens of suitable focal length in the spectacles of such a person.