Anatomy of the orbital septum and associated eyelid connective tissues. Implications for ptosis surgery.

The anatomy of the orbital septum and associated eyelid connective tissues was examined using cadaver dissection, histologic sections, surgical observations, and special radiologic imaging. The embryologic development of the eyelid connective tissues was also reviewed. Examination revealed a distinct layer of fibroadipose tissue in the eyelid and eyebrow posterior to the orbicularis and frontalis muscles, and anterior to the orbital septum. Fibrous septa within the submuscular fibroadipose tissue become contiguous with more compact lamellae of the orbital septum posteriorly imparting a multilayered quality to the orbital septum. Fat within the fibroadipose layer anterior to the orbital septum may be mistaken for the preaponeurotic fat pad by the unwary surgeon and may lead to surgical error. The orbital septum and the levator aponeurosis were found to join 2 to 5 mm above the superior tarsal border (average, 3.4 mm). Recommendations for ptosis surgery based on these anatomic principles are given.