(i) Myopia is the defect of the eye vision due to which a person can see the near objects clearly but cannot see the far objects so distinctly.
Causes of myopia: Myopia is caused :
- due to the elongation of the eye ball.
- due to decrease in the focal length of the eye lens. The eye lens becomes more convergent. Myopia can be corrected by using a concave lens of suitable focal length in the spectacles of such a person.
(ii) The ability of the eye lens to adjust its focal length is called accommodation. However, the focal length of the eye lens cannot be decreased below a certain limit. The maximum accommodation of a normal eye is reached when the object is at a distance of 25 cm from the eyes. Thus, the normal eye is unable to focus an object placed within 10 cm from the eye because all the power of accommodation has already been exhausted.
