Pathomechanism of optic nerve avulsion.

Optic nerve avulsion following peri-orbital trauma is an enigmatic clinical entity. Several mechanisms and ideas have been put forward to derive a logical conclusion, however, each factor independently does not appear to explain the mechanism in a logical way, therefore, here we elaborate the probable chain of events responsible for this complication. During isolated blunt trauma to the orbital framework, the globe continues to move anteriorly without any active resistance, in contrast to the globe, the optic nerve with more delicate bony and soft tissue relations, likely to remain relatively static. Thus the junction between the optic nerve and ocular coat suffers the maximum distractive injury due to anteroposterior tractional forces. In addition to this, physiological Bell's phenomenon may induce torsional tension at this junction leading to further worsening of distractive forces and violent separation of optic nerve from the globe.