Pathomechanism of optic nerve avulsion

Area of Science:

• Ophthalmology
• Trauma Surgery
• Neuroscience

Background:

• Optic nerve avulsion is a rare but severe complication of peri-orbital trauma.
• Existing theories do not fully explain the mechanism of optic nerve avulsion.
• Understanding the biomechanics is crucial for potential preventative strategies.

Purpose of the Study:

• To elucidate the probable chain of events leading to optic nerve avulsion after blunt orbital trauma.
• To explain the biomechanical forces involved in this injury.

Main Methods:

• Conceptual analysis of biomechanical forces during blunt orbital trauma.
• Review of anatomical relationships between the orbital framework, globe, and optic nerve.
• Integration of physiological responses like Bell's phenomenon.

Main Results:

• Blunt trauma causes anterior globe displacement due to lack of resistance.
• The optic nerve, relatively static due to its attachments, experiences maximal anteroposterior traction.
• Physiological Bell's phenomenon can exacerbate tractional forces via torsional tension.

Conclusions:

• Optic nerve avulsion results from a combination of differential movement and torsional forces at the optic nerve-globe junction.
• This mechanism explains the violent separation of the optic nerve following blunt peri-orbital trauma.