Ptosis refers to the droopiness of an eyelid. Ptosis usually occurs in the upper eyelid of one or both eyes and it results from a deficiency in the action of the elevating muscle or its tendon. Ptosis can be congenital or acquired.
Congenital ptosis is either inherited or an isolated birth defect. Congenital ptosis is almost always caused by the inadequate development of the elevating muscle and is noted shortly after birth.
Surgery for muscular ptosis is directed at tightening the elevating muscle tissue or, in severe instances, by connecting the paralyzed lifting mechanism to the healthier muscles of the eyebrow via an internal suspension system. While such procedures can lift the eyelid higher, the dystrophic muscle can never be made normal and so some degree of functional deficiency in opening and closing the eyelid will always persist.
The vast majority of cases of acquired ptosis, which is acquired after birth, are as a result of aging, trauma, muscular and neurologic disease. Rarely, adult ptosis may be caused by muscular disease as well. In acquired ptosis, the elevating tendon deteriorates, rather than the muscle itself. The areas of thinning, localized tears to the tendon, or sometimes complete detachment of the tendon inhibit the ability for the muscle to lift. The surgery is intended to reattach the stretched muscle to its normal location or remove the excess skin that is weighing the eyelid down.