Contribution of the medial orbital floor to endoscopic orbital decompression

This study explores contribution of the orbital floor to mechanical outcomes of orbital decompressions. Endoscopic medial wall orbital decompressions with and without extensive medial orbital floor removal (OFR) were performed on opposite sides of ten thawed fresh-frozen cadaver heads Bone removal was compared on pre- and post-dissection CT scans and after orbital exenteration. Bony removal in the anterior orbital apex was significantly better after OFR (117 vs 66, p < 0.0001). An average of 10.3% (range 0 - 45.5%) of the orbital floor directly under the globe was removed with the OFR technique. The orbital floor preservation (OFP) technique resulted in average bone removal of 3.6 cm2, whereas OFR decompression resulted in average of 5.7 cm2 (p = 0.0003). Post-operative recession of the globe was significant in both arms of the study relative to the unoperated state (OFP averaged 2.99 mm decompression, p = 0.001 and OFR averaged 4.25 mm decompression, p = 0.02). Endoscopic removal of the medial orbital floor when performed in addition to medial wall decompression removes > 60% more orbital bone and an additional 51 of orbital apex bone. Extensive endoscopic removal of the mid-portion of the medial orbital floor results in bone loss beneath the globe itself.