Orbital compartment: effects of emergent canthotomy and cantholysis.

The objective of this study was to determine the effect of orbital decompression procedures on the intraocular pressure (IOP). The orbital compartment syndrome represents an emergency situation. Due to the elevated IOP vision loss may ensue. Several maneuvers including lateral canthotomy are discussed to reduce the IOP. Eight orbits were studied in a fresh frozen cadaveric model (4 specimens). Intraorbital volume was determined by CT volumetry. An orbital compartment syndrome was simulated by injecting viscous material into the orbit. Injected volumes were documented and lateral canthotomy, cantholysis, inferior and superior septolysis were performed. IOP and exophthalmometric measurements were obtained after each intervention. Controlled elevation of IOP was achieved in all specimens. IOP was partially reduced after performing a lateral canthotomy in eight orbits. IOP was significantly and sufficiently decreased under 20 mmHg by inferior cantholysis in seven orbits. An additional superior cantholysis was necessary in two orbits to achieve a complete decompression. Inferior or superior septolysis were not needed to further reduce the IOP. Lateral canthotomy must be followed by an inferior cantholysis to successfully decompress an orbital compartment syndrome in the majority of cases. Occasionally, superior cantholysis may generate additional benefit. Additional inferior and superior septolysis were not shown to provide a beneficial effect when performed after canthotomy and cantholysis.