EFFICACY OF LATERAL CANTHOTOMY AND CANTHOLYSIS IN ORBITAL HEMORRHAGE

Emergent orbital decompression in tense orbital hemorrhage with compro mised ophthalmic blood flow may be achieved with lateral canthotomy, d efined as incision of the lateral canthal tendon, and cantholysis, def ined as canthotomy combined with disinsertion of at least the inferior crus of the lateral canthal tendon. This study was performed to deter mine which procedure, canthotomy, canthal tendon disinsertion, or cant holysis, produced the largest reduction in intraocular pressure after simulated orbital hemorrhage in 10 closed ruminant orbits with retrobu lbar injections of normal saline. Intraocular pressure (IOP) reduction s were measured after canthotomy in five orbits, after lateral canthal tendon disinsertion in five orbits, and after completion of cantholys is in all 10 orbits. Canthotomy produced a mean IOP reduction of 14.2 mm Hg. Canthal tendon disinsertion (CTD) produced a mean IOP reduction of 19.2 mm Hg. Cantholysis produced a mean IOP reduction of 30.4 mm H g, a significantly (p < 0.05) greater reduction in IOP than that produ ced by canthotomy or canthal tendon disinsertion alone. Cantholysis in acute orbital hemorrhage may produce significantly greater reduction in IOP, and thus in intraorbital pressure, and allow better perfusion of orbital tissues than either lateral canthotomy or CTD.