Question
Tue January 01, 2013 By:
 

differenciate presbyopia and hypermetropia

Expert Reply
Tue January 01, 2013

HYPERMETROPIA:

  • it the defect of a human eye, which is able to see far away object clearly but not the nearby objects.
  • the correction lens for this defect is convex lens of suitable focal length or power.
  • causes:

1: decrease in length of thr eye ball.

2: increase in focal length of the eye lens.

PRESBYOPIA:

  • it is the defect of eye during old age, with increase of age the ciliary muscles holding the eye lens weaken and the eye loses some of its flexibility this causes presbyopia.
  • the correction for this lens is a bifocal lens.
  • causes:

1: increase in focal length of eye lens.

2: old age.

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