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Tadashi Matsumoto, Yuta Saito, Takashi Itokawa, tomoaki shiba, Haruo Takahashi, Yuichi Hori; A study of ocular blood flow in oxygen-induced ischemic retinopathy model rats using Laser Speckle Flowgraphy-Micro. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3632.
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© ARVO (1962-2015); The Authors (2016-present)
This study used Laser Speckle Flowgraphy (LSFG)-Micro (Softcare) to examine changes in ocular blood flow at onset of retinopathy in oxygen-induced ischemic retinopathy (OIR) model rats.
Twelve OIR rats were compared with 12 rats reared in room air (Control). The OIR rats were created by rearing Sprague-Dawley rats under oxygen loading in a 50%/24 hour, 10%/24 hour cycle until postnatal day 14 (P14). Pups and dams were moved to room air at P14. Ocular blood flow was measured in P14 and P18 rats using LSFG-Micro. The optic nerve head (ONH) was measured for 4 seconds after dilating the pupil with 0.4% tropicamide. Three measurements were taken within 5 minutes, after which a rubber band was placed on the ONH to analyze ocular blood flow (mean blur rate; MBR). Rats were anesthetized with xylazine and ketamine during measurements. Ocular pressure and blood pressure were measured before MBR to calculated ocular perfusion pressure (OPP). At P18, the rats were sacrificed and retinas in left eyes were fixed, flatmounted and stained with ADPase. Retinal neovascularization (NV) was scored with counting clock hours method (CH). Avascular areas (AVA) were measured as a % of total retinal area (%AVA).
Reproducibility of the MBR had a coefficient of variation (COV) of 1.8 ± 1.1% and interclass correlation coefficient (ICC) of 0.99. MBR and OPP were correlated in Control rats (r = 0.63, p = 0.0021). MBR and body weight were correlated in both OIR rats (r = 0.58, p = 0.0004) and Control rats (r = 0.68, p = 0.0009). Analysis of covariance results were high for MBR in OIR rats (p = 0.0003). In Control rats, CH and %AVA were both 0, while in OIR rates, CH was 4.1 ± 2.8 and %AVA was 19.1 ± 13.2%. A correlation were seen between MBR and CH (r = 0.62, p = 0.0271), %AVA (r = 0.89, p = 0.0003) in OIR on P18.
LSFG-micro produced favorable results in blood flow measurements in neonatal rats. MBR was higher in OIR rats than Control rats, and a correlation were seen between MBR and CH, %AVA, suggesting that MBR could serve as an indicator of OIR severity.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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