Question

Please state the process of near response in vision and describe its physiological significance

Answer 1

To focus the objects which are kept very near to eye, our eye has a near reflex or near response. It is brought together by 3 things-

1. Convergence of both the eyeball - this happens to decrease the felid of vision and to put focus mainly on the object which is kept near.

2. Contraction of pupil

3. Change in curvature of lens brought by contraction of ciliary muscles(accommodation)- this increases the thickness of lens. Increased thickness will result in more bending of light and this in turn will focus the near object more clearly.

Physiological aspect-

This near response is very important because is this response is absent, we won't be able to see the near objects clearly. Example is in the case of presbyopia, in which there is physiological loss of accommodation due to ageing. The near point shifts back and objects kept very close to eye are not focused properly.