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yasushi wada; The longitudinal changes of optic nerve head blood flow of the normal rats using laser speckle flowgraphy.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3000.
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© ARVO (1962-2015); The Authors (2016-present)
There is evidence to suggest that a disturbance of ocular blood flow may be one of the risk factors unrelated to the intraocular pressure (IOP) for the onset and progression of glaucoma. Laser speckle flowgraphy (LSFG) allows in vivo quantitative evaluation of blood flow in the optic nerve head (ONH), choroid and retina. A literature search did not find any reports on LSFG measurement in the ONH of rodent eyes. In this study, we investigated the longitudinal changes of ONH blood flow of normal rats using LSFG, and the reproducibility of LSFG measurement.
Brown-Norway rats (N = 9), 10 weeks of age, were used. Rats were kept under general anesthesia, and their right eyes were dilated with 0.4% tropicamide. IOP, blood pressure, ocular perfusion pressure (OPP), heart rate, and LSFG (LSFG-Micro, Softcare Co., Ltd., Japan) were measured 30 minutes after the start of anesthesia. Three parameters of mean blur rate (MBR) in the ONH was derived from LSFG; MBR in all area (MA), MBR in vessel area (MV), and MBR in tissue area (MT). These parameters were evaluated in each quadrant: superior, inferior, temporal, and nasal quadrants. The coefficient of variation (COV) was calculated from MBR data in three consecutive examinations on the same day. MBR measurements were repeated at 10, 11, 13, 19, 20 weeks of age, and every 5 week until 60 weeks of age thereafter.
The COV of MBR was less than 6.4% in all ONH quadrants. MBR (MA, MV, and MT) in all ONH quadrants increased until 19 weeks of age (MT in the superior quadrant, P = 0.019; MT in the nasal quadrant, P = 0.004; MT in other quadrants, and MV and MA in all quadrants, P < 0.001), but was stable thereafter until 60 weeks of age. MBR (MA) in the inferior quadrant was significantly higher than the temporal quadrant from 19 to 55 weeks of age. There were no significant changes in IOP, blood pressure and OPP during the experimental period.
The ONH blood flow in rats may change overtime; increase from 10 to 19 weeks of age, and then become stable until 60 weeks of age. The ONH blood flow may exhibit regional differences; higher blood flow in the inferior quadrant than the temporal quadrant. LSFG is a reliable and useful method for longitudinal evaluation of ONH blood flow in rats.
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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