Abstract
Purpose :
Non-arteritic ischemic optic neuropathy (NAION) is caused by a sudden blood insufficiency for the optic nerve and is a major cause of optic nerve dysfunction. A rodent model of NAION (rNAION) was previously developed. However, the evidence that optic nerve head blood flow is reduced in rNAION has not been demonstrated in vivo. Our purpose was to evaluate optic nerve head blood flow in normal and rNAION rats, in vivo, using laser speckle flowgraphy (LSFG).
Methods :
We used male Sprague-Dawley rats (200–240 g; Kyudou, Kumamoto, Japan). The rats were anesthetized with intramuscular ketamine/xylazine (100 mg/kg and 10 mg/kg, respectively). To induce rNAION, Rose Bengal (RB) (2.5 mM, 1 mL/kg) was injected into the tail vein. After administration of RB, the left optic nerve head was photoactivated using a 514 nm argon green laser (Coherent Ultima 2000 SE Argon) with an approximate 500 μm spot size for 12 seconds. We measured optic nerve head blood flow in normal rats (n=10) and in acute phase rats 1 day after induction of rNAION (n=6) using LSFG (LSFG-Micro, Softcare Co., Ltd, Fukuoka, Japan). The mean blur rate (MBR) of the vascular area (MV) and mean tissue area (MT) were used as the indicators of blood flow. We compared the MBR between the right eye and the left eye in the normal rats and rNAION rats. For statistical analysis, the Mann-Whitney U-test was used. P values <0.05 indicated statistical significance.
Results :
In normal rats, there was no significant difference of MV or MT between the right eye and left eye (MV: P=0.473; MT: P=0.140, respectively). In the rNAION rats, the MBR of involved eyes was 78.8% in MV and 81.5% in MT, which was lower than that of unaffected eyes. The ratios of MV and MT in the left eyes of rNAION rats were significantly smaller than those in the right eyes (MV: 0.788, P=0.004; MT: 0.815, P=0.03, respectively)
Conclusions :
Our results indicated that optic nerve head blood flow of rNAION rats was reduced in the acute stage at 1 day after induction.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.