Why do Cat's Eyes Change Shape and What Do These Shapes Mean?

Have you ever wondered, “why do cats’ eyes change shape?” In fact, their eyes don’t change shape; their pupils do. A cat’s pupils can change shape from a narrow slit to wide circles, which is usually in response to light. Their pupils can dilate up to 135 times their narrowed size, which is over 100 times more than humans can! By dilating their pupils, cats can see in dim light without being blinded by sunlight. 

Cats’ eyes can also change in response to their emotions; therefore, understanding what your cats’ pupils mean can help you know how they are feeling. Your cat’s eyes can tell you a lot when paired with how other parts of their body are behaving, such as their whiskers, head position, and body position. This means their body language and eyes can tell you how they might be feeling in a certain situation. Learning about your cat’s eye meanings and body language is also beneficial for building a bond with your cat.

What do cat eye shapes mean?

Interesting research into cats’ eye shape meanings found that their pupil shape is dependent on their lifestyle. As cats are known for having natural hunting instincts, their eyes change to help them with this. Cats have vertical slit pupils to aid their hunting during the day and at night. The vertical slit allows them to judge distances in order to successfully pounce on their prey. 

However, there are many other meanings behind your cat’s eyes changing shape. So, we’ve created a list of cat’s eye shape meanings to help you understand your kitty more!

Dilated pupils

This cat pupil meaning tells you that your cat is emotionally aroused; this could be because of fear, surprise, or excitement. Some cats’ pupils dilate in response to catnip as they are aroused by the scent. However, dilated pupils could also mean something more serious and show that your cat is in pain. In this case, it’s a good idea to check out the rest of their body to determine if anything is wrong. 

If your cat has very wide ‘saucer’ pupils and you see their body become tense, as well as their ears flattening and tail swishing, it shows they are unhappy in their current situation. Paired with your cat’s eye shape, this body language means they are feeling threatened or anxious. If you notice your cat showing these signs of unease, it’s important to work out what is worrying them so you can put measures in place to help them feel settled again. FELIWAY® Optimum can be a great way to reinstate the calm they need to make them feel more relaxed and enhance their serenity.

Narrow pupils

Constricted cat eyes can mean they are feeling threatened. This can also be accompanied by ‘squinty’ eyelids, which they use as a means of protecting their eyes from any injury.

‘Normal’ size pupils

A relaxed cat's eye means that they are calm. When your cat is in this state, they will relax their eyelids and the muscle tension around their head. If a cat is coming towards you like this with a vertical tail, it’s a signal of a friendly greeting. If your cat looks at you with heavy eyelids and slow blinks, this is a sign of a contented cat showing you affection. 

Stare

Cats will often stare at an object if they are interested in it. During this state, cats are paying high attention and preparing to pounce if their target moves. On the other hand, if a cat is staring at a person or other cats, an unblinking stare is usually a message that suggests they stay away. 

If your cat is showing this behavior towards you, it’s important to avoid staring at your cat. Instead, if you see they are showing signs of unease, consider how you can make them feel more comfortable. They may need some space and for you to bring any interaction to an end. They may also be feeling pain, so make sure to check with your vet for any underlying health problems. If you see your cat feeling uneasy in situations regularly, you can also use FELIWAY® Optimum to provide enhanced serenity for your cat.

Different sized pupils

Different cats’ pupils can mean they have anisocoria, a type of medical issue. If you notice your cat’s eyes look to be different sizes, it’s important to contact your vet.

Other things to keep an ‘eye’ on

Regularly check on the general health of your cats’ eyes to look for signs of redness, discharge, or swelling. If you notice your cat is bumping into things, has less interest in playing, and isn’t jumping on and off things as easily as before, this can alert you that they have developed issues with their sight. You may also notice that they have widened pupils that don’t change. In each of these situations, it’s important to check with your vet to identify any medical causes.

Interestingly, all kittens are born with blue eyes, which then change color within the first six weeks of their lives as melanin develops. By 3 months, their eye color will be set and should remain the same as they grow. However, if you do notice your cat's eye color changing after 3 months, you should once again contact your vet.