Till date, a lot of impenetrable mysteries still surround the nature of the cherry eye ailment. The anatomical analysis of the ailment shows that it’s related to a defective nictitating membrane. The nictitating membrane (also known as the third eyelid), is a connective tissue underlining the lower eyelids of dogs. It is responsible for eye lubrication and the production of the tear film, and also acts as a protective shield against dust and other foreign objects. The third eyelid also comes with a tear gland that supplies the dog’s eye with 35%-50% of the total moisture required. Hence it’s a crucial component of the dog’s ocular system.