Droopiness of the upper eyelid (ptosis) results from a deficiency in the action of the elevating muscle (levator muscle) or its tendon (levator aponeurosis).
Congenital ptosis (either inherited or an isolated birth defect) is almost always caused by the inadequate development of the levator muscle itself and is noted shortly after birth. Rarely, adult ptosis may be caused by muscular disease as well, especially in such degenerative conditions as myasthenia gravis.
Surgery for muscular ptosis is directed at tightening the levator muscle tissue (by partial resection) 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 (slight to marked) of functional deficiency (both opening and closing) will always persist.
Fortunately, the vast majority of cases of acquired ptosis (that is, onset after birth) are related to a deterioration of the levator aponeurosis (tendon) rather than the muscle itself, which remains healthy. The aponeurosis develops areas of thinning, localized tears, or sometimes complete detachment and is no longer able to transmit the lift of the levator muscle to the margin of the eyelid.
Correction entails an exploration of the interior eyelid to determine the precise location and nature of the defect followed by a reinforcement or tucking of the weakened areas. If properly repaired, the function of the levator system is restored to a state approaching normal.
In adults, ptosis repair is always performed under local anesthesia with sedation to allow for patient cooperation during surgery. Such patient feedback is necessary to help the surgeon achieve not only a satisfactory level of lift but also the restoration of normal lid contour and acceptable symmetry between the two sides.
A droopy eyelid (ptosis) should not be confused with a baggy eyelid (excess eyelid skin and fat), which is a much more common and unrelated cosmetic condition. Even in the best of hands, healing may be prolonged and approximately one in six eyelids will require a second operation to achieve the optimal final result. For this reason, many ophthalmologists and plastic surgeons refer their patients with ptosis to an experienced eyelid specialist.
Insider's Guide to Blepharoplasty
Chapter 15: Repair of Eyelid Ptosis
The Eyelid Owner's Manual
Ptosis Photos - Before and After
