A cat's eyes are very expressive and can tell you a lot about her mood and health. Sometimes dilated pupils can be a signal that something's not quite right. Treat and Trick How to Teach Your Cat! Cat training The pupil constricts or dilates (enlarges) according to the amount of light that enters the eyes, with both pupils normally dilating in dim light and constricting in bright light.Cats eyes dilated meaning. This is a clear sign of fear and fear, which can be