DEFECTS OF VISION

A normal eye can see all objects situated at a distance greater than 25 cm. using its power of accommodation. But due to certain abnormalities, elongation, distortion or even distortion of eye ball, the defects of vision arise and the eyes become unable to accommodate itself to various distances, then it is said to be defective. The defects are mainly of five types;

1-) Short-sightedness or Myopia, 

2-) Long-sightedness or Hypermetropia,

3-) Old sight or Presbyopia,

4-) Astigmatism,

5-) Colour blindness.