Ptosis (also called "droopy eyelid") is when the upper eyelid droops down. It may droop just a little, or it may cover half the eye or more. Ptosis (pronounced "toe-sis") can block kids' vision. Some children are born with droopy eyelid or it may show up later. At Nemours, our pediatric eye specialists are trained to detect ptosis and provide expert treatment for kids.