“Cherry eye” is the common name for a medical condition known as a prolapsed nictitating membrane, prolapsed third eyelid, or third eyelid gland prolapse. The third eyelid, or nictitating membrane, is the fleshy, pink part next to the eye in the eye socket. This membrane is actually a flap of tissue that contains a gland that secretes tears and is usually not easily seen. It should be flat and against the corner of the eye socket but in a dog with cherry eye, it gets enlarged, flips over, and protrudes or prolapses making it abnormally visible.
Dogs can be born with Cherry eye but more often it develops over time. The condition is most commonly seen in dogs that are 2 years of age or younger but some breeds are more likely to develop cherry eye than others. Surgical repositioning of the gland, not excision, is the recommended treatment since it preserves the important function of tear production.
Here is a picture of a rescue patient that recently had cherry eye surgery (before picture)