The influence of orbital and eyelid anatomy on the palpebral aperture.

A multitude of factors influence the palpebral aperture: the surrounding bony orbital anatomy, the internal orbital volume, the integrity of the eyelids, and their muscular and tarsoligamentous support system. Furthermore, it is influenced by the relative amount of associated periorbital skin, fat, and soft tissues. Unique individual combinations of the above eyelid and orbital anatomic influences cause the variations in the palpebral apertures.