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K Guan, C Hudson, J FlanaganMulti-Disciplinary Laboratory for the Research ofSight Threatening Diabetic Retinopathy; Variability and Repeatability of Retinal Blood Flow Measurements Using the Canon Laser Blood Flowmeter . Invest. Ophthalmol. Vis. Sci. 2002;43(13):515.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the within session variability and between session repeatability of the Canon Laser Blood Flowmeter (CLBF) model 100. Methods: The CLBF simultaneously determines centerline blood velocity (mm/sec) and vessel diameter (µm) of the retinal arterioles and venules. It calculates the flow in µl/min based on the Poiseuille principle. One eye of eleven normal subjects (mean age 34 ± 7.9 years) was randomly chosen. A minimum of 5 sets of measurements were taken of a temporal arteriole approximately 1 disc diameter from the edge of the optic nerve. Two separate sessions were undertaken within a 2 week period. Blood pressure and intraocular pressure were measured. Axial length was also measured to correct for the impact of magnification on blood flow parameters. All measurements were taken by a single operator (KG). For each subject, the co-efficient of variation (CoV) was calculated for each session and the co-efficient of repeatability (CoR) was calculated for between session repeatability. Results: The individual CoVs for diameter, velocity and flow ranged from 0.8%-6.2% (median 2.5%), 10.6%-40.4% (median 23.4%) and 10.9%-42.2% (median 22.1%), respectively. The CoR for diameter, velocity and flow were 5.0µm (relative to a mean effect of 104.4), 3.7mm/sec (relative to a mean effect of 28.5), 1.2µl/min (relative to a mean effect of 7.3), respectively. The magnitude of between session differences for diameter, velocity and flow ranged from 0.2µm to 4.6 µm, 0.1 mm/sec to 5.2 mm/sec and 0.0 µl/min to 1.7 µl/min, respectively. Conclusion: The CLBF gives consistent and repeatable measurements of blood flow within retinal arterioles in normal subjects. This instrument potentially offers the opportunity to quantifiably track retinal blood flow disturbances in various ocular diseases such as diabetic retinopathy.
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