Evaluation of optic nerve head blood flow in normal rats and a rodent model of non-arteritic ischemic optic neuropathy using laser speckle flowgraphy.

Purpose: To evaluate optic nerve head (ONH) blood flow in normal rats and a rodent model of non-arteritic ischemic optic neuropathy (rNAION) in vivo using laser speckle flowgraphy (LSFG).

Methods: Rats were under general anesthesia; to induce NAION, Rose Bengal (RB) was injected into the tail vein. After the administration of RB, the left ONH was photoactivated using an argon green laser. We measured ONH blood flow in the normal rats and the rNAION group (at 1, 3, 7, 14, and 28 days after the induction of NAION) using an LSFG-Micro. We used the mean blur rate (MBR) of the vessel region (MV) and MBR of the tissue region (MT) as indicators of blood flow. We compared the MBR of the right and left eyes in both the normal rats and the rNAION group.

Results: In the normal rats, there were no significant differences in MV or MT between the right and left eyes. In the rNAION group, the MV and MT of the affected eyes were significantly lower than those of the unaffected eyes at all time points. There were significant differences between the left/right MV and MT ratios seen before the induction of NAION and those observed at 1, 3, 7, 14, and 28 days after the induction of NAION. However, there were no significant differences in these parameters among any of post-NAION induction time points.

Conclusion: Our results indicated that the ONH blood flow of the rNAION rats fell in the acute and chronic phases.