Quantification of histological changes after calibrated crush of the intraorbital optic nerve in rats.
BACKGROUND
Traumatic optic nerve lesions (TONL) are probable but unpredictable consequence after severe midface or skull base trauma. Based on a previously described rat model, the authors developed a new model in order to simulate optic nerve crush during trauma on the optic canal.


METHODS
To achieve a calibrated TONL, a microinjuring device was designed that made it possible to assess the correlation between a defined trauma and the neuronal degeneration in the rat retinal ganglion cell (RGC) layer. This device is based on a small dynamometer mounted onto a conventional micromanipulator. The supraorbital approach was chosen to expose the extracranial optic nerve.


RESULTS
In this rat model (n=100, Wistar strain) the parameters of "force" and "time" could be precisely monitored during the experiment. The decrease in the mean number of retinal neurons (N) according to the pressure exerted (2-30 cN x mm(-2)) on the optic nerve was linear for 1, 6, and 15 minutes of injuring time; the decrease in N for varying injuring forces also appears to be nearly linear.


CONCLUSIONS
The results show that this model provides a reliable method for studying quantitatively the anatomical effects of TONL on the RGC layer and the optic nerve itself, and may allow the design of treatment strategies following TONL.
Gellrich
Nils-Claudius
NC
Department of Oral and Maxillofacial Surgery, University Hospital of Freiburg, Freiburg, Germany. gellrich@zmk2.ukl.uni.freiburg.de
Schimming
Ronald
R
Zerfowski
Martin
M
Eysel
Ulf Theodor
UT
D000818:Animals; D002452:Cell Count; D004195:Disease Models, Animal; D008297:Male; D009409:Nerve Crush / Q000379:methods; D009410:Nerve Degeneration / Q000473:pathology; D020221:Optic Nerve Injuries / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D010775:Photic Stimulation; D051381:Rats; D017208:Rats, Wistar; D012025:Reflex, Pupillary; D012165:Retinal Ganglion Cells / Q000473:pathology; D013314:Stress, Mechanical