Adult ptosis may also occur as a complication of other diseases involving the levator muscle or its nerve supply, such as neurological and muscular diseases and, in rare cases, tumors of the eye socket. Congenital ptosis is often caused by poor development of the levator muscle that lifts the eyelid. Although it is usually only a problem with a drooping eyelid, a child born with ptosis may also have eye-movement abnormalities, muscular diseases, lid tumors, or other tumors, neurological disorders or refractive errors.