question_answer 43)

  When do we consider a person to be myopic and hypermetropic? Explain using diagrams how the defects associated with myopic and hypermetropic eye can be corrected?

Answer:

                  Myopic This term is used to define shortsightedness. Light from a distant object forms an image before it reaches the retina. This could be because the eye is too long or the cornea or crystalline lens is too strong. A myopic person has clear vision when looking at objects close to them but distant objects will appear blurred. To correct this defects a concave lens (minus powered) is placed in front of a myopic eye, moving the image back to the retina and clarifying the image. Hypermetropic It means long sightedness, and, in which the image of a nearby object is formed behind the retina. This could be because the eye is too short or the cornea or crystalline lens does not refract the light enough. A hypermetropic person may have blurred vision when looking at objects close to them and clearer vision when looking at objects in the distance. To correct this defects a convex lens (plus powered) in front of a hypermetropic eye, the image is moved forward and focuses correctly on the retina.