CLINICAL AND EXPERIMENTAL-STUDY ON TRAUMA TIC OPTIC-NERVE LESION

Background: Traumatic optic nerve lesions (TONL) range from temporary affection of vision to avulsion of the optic nerve; often they are ass ociated with more complex injuries. Usually Tonl are not regarded as a n emergency. Up to now, we lack knowledge on the dependency of strengt h and duration of optic nerve lesions and the point of no return for a fferent disorders of the visual pathway.Materials and methods: We perf ormed a prospective study on 50 patients with severe midface and skull base fractures in order to find characteristic ophthalmological, compu ter tomographic und electrophysiological findings as indicators of TON L, independent of patient cooperation. We used an animal model (Wistar rats; n = 117)to study calibrated optic nerve lesions and the resulti ng neurodegeneration in the retinal ganglion cell (RGC) layer quantita tively. Results: The electrophysiological investigation of the visual system (flash VEP/ERG) proved to be highly specific(0.97) and sensitiv e (1.0) for detecting TONL (n = 18). In the rat model, we could demons trate a linear relationship between total neuron number reduction and strength and duration of calibrated optic nerve lesion. Conclusions: E xperimental results indicate that optic nerve decompression is useful only within the first hours after TONL to reduce secondary optic nerve lesion. Indication for optic nerve decompression requires early detec tion of TONL, which is made possible by the combination of flash VEP/E RG.