Orbital and globe rotation: the role of the periorbita.

We hypothesize that excyclorotation of the globe and extraocular muscle cone associated with external orbital rotation around each orbital axis in craniofacial conditions could be at least partially corrected by leaving the anterior periorbita (periosteum lining the orbit) attached to the surgically rotated portion of the orbit. This hypothesis was tested by comparing the degree of rotation of the globe in response to internal rotation of the anterior orbit, leaving the periorbita attached to the rotated portion of the orbit on one (study) side, and stripping the periorbita on the opposite (control) side, in nine fresh cadavers. There was a highly significant difference (P < 0.0001) between the study and control sides. The possible extrapolations of this finding to the clinical situation are discussed.