Measurement of microcirculation in the optic nerve head by laser speckle flowgraphy and scanning laser Doppler flowmetry

PURPOSE: To evaluate and compare blood flow measurements by laser speckle f lowgraphy and scanning laser Doppler flowmetry in the optic nerve head of n ormal volunteers, a METHODS: This prospective study included 60 eyes of 60 normal volunteers (5 0.0 years; range, 21 to 77 years). Measurements were taken at the temporal neuroretinal rim away from visible vessels, The square blur rate, a quantit ative index of relative blood velocity, was measured by laser speckle flowg raphy. Using scanning laser Doppler flowmetry, volume, flow, and velocity w ere measured at the same neuroretinal rim locations, RESULTS: The average square blur rate, volume, flow, and velocity were 7.11 +/- 1.65, 7.74 +/- 3.19, 151.85 +/- 70.63, and 0.53 + 0.23 arbitrary units , respectively (n = 60). Square blur rate correlated significantly with flo w and velocity (r = .361, P = .005; r = .359, P = .005, respectively). Howe ver, there was no significant correlation between square blur rate and volu me (r = .101, P = .441). Although square blur rate decreased significantly with increasing age (r = -.375, P = .003), volume, flow, or velocity showed no significant correlation with age (r = -.249, P = .054; r = -.166, P = . 205; r = -.143, P = .275, respectively). Square blur rate also decreased si gnificantly with mean blood pressure (r = -.315, P = .014), but volume, flo w, or velocity showed no significant correlation with mean blood pressure ( r = -.159, P = .225; r = -.059, P = .654; r = -.043, P = .742, respectively ). CONCLUSION: We found only a weak correlation between the blood flow indexes , as measured by laser speckle flowgraphy and scanning laser Doppler flowme try because of basic differences in the principles of measure ment, (C) 200 0 by Elsevier Science Inc. All rights reserved.