An optical coherence tomography study on degeneration of retinal nerve fiber layer in rats with autoimmune optic neuritis.

PURPOSE: The aim of the present study was to evaluate the ability and accuracy of spectral domain optical coherence tomography (OCT) for in vivo monitoring of retinal ganglion cell degeneration in a rat model of myelin oligodendrocyte glycoprotein-induced optic neuritis.
METHODS: First, OCT imaging was established for imaging of all retinal layers in Brown Norway rats. Second, thickness measurements of retinal nerve fiber layer (RNFL) were performed by periodically imaging during the development and progression of autoimmune optic neuritis. Third, the reproducibility of OCT measurements was determined by comparing RNFL measurements of two independent investigators. Fourth, OCT data were correlated with histopathology obtained ex vivo after the final imaging session.
RESULTS: Results showed that RNFL thickness declined significantly before clinical manifestation of the disease and decline progresses continuously during the disease course. RNFL thickness measured by OCT had good repeatability and also corresponded with histomorphometric measurements. The reproducibility was limited because of the post-processing analyses performed by manual measurements.
CONCLUSIONS: In summary, it is shown here for the first time that OCT can reliably monitor neurodegeneration in an experimental model of autoimmune optic neuritis in rodents. Moreover, in comparing RNFL thickness decline with histopathological analyses of the optic nerve, these results suggest an early, and in part, inflammation-independent process of RNFL degeneration in autoimmune optic neuritis.