Pupils

The cat (Ema) picture is courtesy of " fmsbotelho " from flickr.

The cat's pupils contract in strong light, in order to defend the retina.

There is no need for the pupil to be closed completely because the eye lids can do that.

When the light is very very strong the pupil will contract to the end and will become closed completely, but only in the middle, tiny aperture will be left on the corners.

In the picture the pupils shows it is a medium strong light.