Eyelid agenesis refers to the absence of a portion of the eyelid. In cats, this usually involves absence of the outer aspect of the upper eyelid. Depending on the amount of eyelid missing, affected cats may have no clinical signs or may have severe surface inflammation. Small defects can usually be treated by cryosurgery (freezing). Large defects usually require a blepharoplastic procedure to make new eyelid tissue.
The images below show the eye of a cat with severe eyelid agenesis before and 6 months after surgery. The new eyelid is functional and has allowed corneal health to return.