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R.D. Ferguson, D.X. Hammer, S.A. Burns, A.E. Elsner; Retinal Hemodynamic Imaging with the TSLO . Invest. Ophthalmol. Vis. Sci. 2004;45(13):1137.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: A new method of stabilized Doppler Flowmetry (SDF) has been demonstrated in human subjects using the tracking scanning laser ophthalmoscope (TSLO). A stabilized display has been integrated into the TSLO for characterization of retinal blood flow response to visual stimuli. Methods: Retinal tracking and quasi–confocal line–scanning imaging enables high–speed, non–aliasing speckle imaging of the retina. Images cubes of 512 x 512 spatial pixels by 512 temporal pixels at a 7.5Khz line rate are acquired, and significantly higher rates and resolutions are possible. Resolved frequencies span from 14Hz to 3.75KHz. Image scans require up to thirty seconds to complete, but precision retinal tracking aligns each pixel in real time so that individual pixel spectra are not perturbed by eye motion. Wide field (to 40 deg), large dynamic range retinal blood flow measurements permit visualization of flow at both higher and lower rates than other imaging flowmetry systems, and in discrete velocity ranges with lower noise. Results: Seven normal subjects and three patients have been scanned with less than 300µW of 790nm laser light. DC reflectance–normalized FFT image cubes divided into octave bands of Doppler frequency reveal different segments of the branching structures in retinal and choroidal circulation according to volume and flow rate (correlated with vessel size), and the distribution of the pulsatile flow amplitude across the retina. Abnormal perfusion patterns appear to be correlated with eye disease. Conclusions: Wide field, large dynamic range, stabilized Doppler Flowmetry provides dye–free, dynamic angiographic images which are suitable for direct comparison with conventional angiography.
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