Evaluation of inner retinal thickness around the optic disc using optical coherence tomography of a rodent model of nonarteritic ischemic optic neuropathy.

PURPOSE: To clarify the usefulness of optical coherence tomography (OCT) for the objective and quantitative evaluation of retinal nerve fiber layer (RNFL) thickness around the optic disc in a rodent model of nonarteritic ischemic optic neuropathy (rNAION).

METHODS: Inner retinal thickness was measured using OCT before and after rNAION induction. The thicknesses of the RNFL and the inner plexiform layer (IPL) were measured using a histologic preparation before and 56 days after induction. We compared the inner retinal thickness measured by OCT with that measured by the histologic preparation.

RESULTS: The mean inner retinal thickness around the optic disc of normal rats measured using OCT was similar to that measured using a histologic preparation (73.50 ± 4.94 vs. 75.94 ± 5.90 μm). The mean inner retinal thickness of rNAION significantly increased until the 7th day, returned to baseline on the 14th day, and decreased until the 90th day after induction. On the 56th day after rNAION induction, histologic measurements indicated that the mean RNFL thickness had decreased but that the IPL thickness was similar to that at baseline.

CONCLUSION: The mean inner retinal thickness measured by OCT correlated with the RNFL thickness of rNAION. OCT is useful for the objective and quantitative evaluation of RNFL thickness around the optic disc in a model of rNAION.