Another big part of the pose. The eyes should be open, alert and bright. No part of the eyelid should cover the eye at all for a good pose.
Now, look at this example.
This is an often problem from calicos: droopy eyelids. Its bad enough the eyelids are shown, but they are also on differnt levels. This will knock the pose out of placement quickly. Other problems are "worried eyes" or "angry eyes," where the eyelids points down or up. Avoid these.