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.

eye of the tiger

The cat with the glowing eyes picture is courtesy of  francesco12corde

The cats cornea has two kinds of cell receptors 

The cone cells for color and the rod cells for contrasts, same as in the human eyes.

Cats eyes has more cone cells than in our eyes, so they see better at night, and in low light, but they have less rod cells so they cant see details like us. 

Cats Eyes

Cats eyes -turquoise color is courtesy of Tambako the Jaguar .
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The cats eyeballs are rounder and shorter than our eyes. it gives them a wider angle vision.
When I looked for my cat, and found her under the bad she looked up at me twisting her head back and up. I had the feeling she sees me good but I didn't understand how. Now I know - She has a wider angle vision.