You are asking about cat eye anatomy. We'll give you a brief overview here but we have a very good in-depth article about the “Structure and Function of the Eye in Cats” which is very helpful - for more information click here.
The eyes allow cats to have a sense of sight. Cat eye anatomy is made up several parts. The main structures include the orbit (which is the bone cavity that the eyeball is in), the eyelids (including a third eyelid), the conjunctiva (thin tissue that lines the eyelid), the eyeball it self, the inside of the eyeball, and lacrimal system (tear glands and tear ducts). There is a lot to cat eye anatomy! The function to the eye is to allow the cat to have vision. Cats can get many different types of eye diseases and there are many different tests that can be done to determine the underlying eye disorder. For more information about cat eye anatomy, click on the link above.