"Round-the-Clock" Surgical Access to the Orbit.

Objective To describe an algorithm to guide surgeons in choosing the most appropriate approach to orbital pathology. Methods A review of 12 selected illustrative cases operated on at the neurosurgical department of University of Pittsburgh Medical Center over 3 years from 2009 to 2011 was performed. Preoperative coronal magnetic resonance imaging and/or computed tomography views were compared using a "clock model" of the orbit with its center at the optic nerve. The rationale for choosing an external, endoscopic, or combined approach is discussed for each case. Results Using the right orbit for demonstration of the clock model, the medial transconjunctival approach provides access to the anterior orbit from 1 to 6 o'clock; endoscopic endonasal approaches provide access to the mid and posterior orbit and orbital apex from 1 to 7 o'clock. The lateral micro-orbitotomy gives access to the orbit from 8 to 10 o'clock. The frontotemporal craniotomy with orbital osteotomy accesses the orbit from 9 to 1 o'clock; addition of a zygomatic osteotomy to this extends access from 6 to 8 o'clock. Conclusions Combined, the approaches described provide 360 degrees of access to the entire orbit with the choice of the optimal approach guided primarily by the avoidance of crossing the plane of the optic nerve.