RT Journal Article
SR Electronic
T1 Computer modelling study of the mechanism of optic nerve injury in blunt trauma
JF British Journal of Ophthalmology
JO Br J Ophthalmol
FD BMJ Publishing Group Ltd.
SP 778
OP 783
DO 10.1136/bjo.2005.086538
VO 90
IS 6
A1 S Cirovic
A1 R M Bhola
A1 D R Hose
A1 I C Howard
A1 P V Lawford
A1 J E Marr
A1 M A Parsons
YR 2006
UL http://bjo.bmj.com/content/90/6/778.abstract
AB Aim: The potential causes of the optic nerve injury as a result of blunt object trauma, were investigated using a computer model. Methods: A finite element model of the eye, the optic nerve, and the orbit with its content was constructed to simulate blunt object trauma. We used a model of the first phalanx of the index finger to represent the blunt body. The trauma was simulated by impacting the blunt body at the surface between the globe and the orbital wall at velocities between 2–5 m/s, and allowing it to penetrate 4–10 mm below the orbital rim. Results: The impact caused rotations of the globe of up to 5000°/s, lateral velocities of up to 1 m/s, and intraocular pressures (IOP) of over 300 mm Hg. The main stress concentration was observed at the insertion of the nerve into the sclera, at the side opposite to the impact. Conclusions: The results suggest that the most likely mechanisms of injury are rapid rotation and lateral translation of the globe, as well as a dramatic rise in the IOP. The strains calculated in the study should be sufficiently high to cause axonal damage and even the avulsion of the nerve. Finite element computer modelling has therefore provided important insights into a clinical scenario that cannot be replicated in human or animal experiments.