Ptosis refers to a drooping of the upper eyelid. It can be unilateral or bilateral, depending on whether it affects one eye or both, and is caused by a deficiency of the "levator" muscle of the upper eyelid.
Several factors can be the cause of ptosis:
In the case of aging, the eyelid muscle thins and may sag with age.
A neuromuscular disorder, ptosis can then be the first sign of a muscle disease; trauma, such as a blow to the eyebrow arch; or a congenital predisposition.
The main treatment is based on a simple surgical procedure. It involves "re-attaching" the upper eyelid to the muscle. Health insurance will not cover this procedure if the purpose is solely aesthetic.