ENTROPION, which is a rolling-in of the eyelid. This causes the hair on the surface of the eyelid to rub on the eyeball, which is both painful and often causes corneal ulcers or erosions. The corneal damage can also result in corneal scarring, which can interfere with vision. Usually the dog will squint and tear excessively. However, many flat-faced dogs with medial entropion (involving the inside corner of the eyes) show no obvious signs of discomfort.
Entropion is treated by surgical correction ("blepharoplasty"), which is essentially plastic surgery. Excessive folds and sections of facial skin are removed, and the eyelids tightened. It is uncommon for entropion to recur after surgery unless the entropion is quite involved, particularly in the Shar Pei breed. Very young puppies with entropion will often have "lid tacking" performed (rather than plastic surgery), in which temporary lid sutures are placed to roll out the lids. Often, these puppies do not require permanent plastic surgery once they have matured and "grown into" their facial skin. Permanent plastic surgery is usually not performed in puppies less than 5 or 6 months of age, giving the dog some time to develop its mature head conformation.
Dogs with inherited entropion should not be bred, as they can pass the trait on to their offspring. The Canine Eye Registration Foundation (see CERF information) publishes a list of breed-specific breeding recommendations for purebred dogs with entropion.