The cat's pupils are different sizes.
Under normal circumstances, a cat's pupils should be the same size or in the same position. For example, in bright daylight, both pupils will narrow into a line of equal length; while in dim light at night, the pupils can dilate to absorb more light in order to see objects more clearly.
If a cat's pupils are different sizes, it's due to genetics, meaning the cat was born with different pupil sizes. If it doesn't affect the cat's normal life, the owner doesn't need to worry.
If the pupil shrinkage is caused by external injury, the cat needs to be taken to a reputable ophthalmology veterinary hospital for examination and timely treatment.
