Question

function of iris

Answer 1

The iris separates the anterior and posterior chambers of the eyeball. The iris, by contraction and dilatation, regulates the entrance of light into the eye. The iris controls the size of the pupil. For spherical refracting lenses, like the one in your eye rays that are further from the optical center are bent more than those closer to the center. The result is that when the image is formed on the retina, it may be slightly out of focus. The iris reduces the number of these rays by forming a barrier over the parts of the lens in the eye which might cause this, and thus producing a more sharply focussed image on the retina.