Nikolaus Luft1, Piotr A Wozniak2, Gerold C Aschinger3, Klemens Fondi4, Ahmed M Bata4, René M Werkmeister4, Doreen Schmidl5, Katarzyna J Witkowska4, Matthias Bolz6, Gerhard Garhöfer4, Leopold Schmetterer7. 1. Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria 2Department of Ophthalmology, Kepler University Hospital, Linz, Austria 3University Eye Hospital, Ludwig-Maximilians University, Munich, Germany. 2. Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria 4Department of Ophthalmology, Medical University of Warsaw, Warsaw, Poland. 3. Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria 6Institute of Applied Physics, Vienna University of Technology, Vienna, Austria. 4. Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria. 5. Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria 5Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria. 6. Department of Ophthalmology, Kepler University Hospital, Linz, Austria. 7. Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria 5Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria 7Singapore Eye Research Institute, the Academia, Singapore 8Lee Kong Chian School of Medicine, Nanyang Technological University, Novena Campus, Singapore.
Abstract
PURPOSE: This study evaluated the validity of retinal perfusion measurements using laser speckle flowgraphy (LSFG) by means of in vitro experiments and direct comparison with dual-beam Doppler optical coherence tomography (D-OCT) in a healthy Caucasian population. METHODS: The flow velocity of scattering solution pumped through a glass capillary was measured at 17 different flow velocities (range, 0.5-47 mm/s) using LSFG. The flow within the glass capillary was produced by a computer-controlled infusion pump. In vivo, three consecutive LSFG scans were obtained in 20 eyes of 20 healthy Caucasian subjects before and after pharmacological pupil dilation. Relative flow volume (RFV), the primary output parameter of LSFG, was comparatively validated relative to absolute measurements of retinal blood flow and velocity as obtained from D-OCT. RESULTS: In the in vitro experiments, RFV was found to saturate at a level of approximately 700 arbitrary units (au) or 23.5 mm/s of actual velocity. In vivo, RFV was in significant agreement with absolute blood flow measurements as obtained from D-OCT in arteries (r = 0.69, P = 0.001) and veins (r = 0.74, P < 0.001). However, linear regression analysis revealed significant positive zero offset values for RFV of 223.4 and 282.7 au in arteries and veins, respectively. CONCLUSIONS: Measurements of RFV were successfully obtainable, reproducible, and not influenced by pharmacological pupil dilation. Nevertheless, our data revealed flaws in the LSFG method of measuring retinal perfusion in Caucasians. Adjustment to the technique is required to address apparent issues with RFV, especially saturation effects with higher arterial flow rates. The present dataset may provide a valuable tool to do so. (Clinicaltrials.gov number NCT02582411).
PURPOSE: This study evaluated the validity of retinal perfusion measurements using laser speckle flowgraphy (LSFG) by means of in vitro experiments and direct comparison with dual-beam Doppler optical coherence tomography (D-OCT) in a healthy Caucasian population. METHODS: The flow velocity of scattering solution pumped through a glass capillary was measured at 17 different flow velocities (range, 0.5-47 mm/s) using LSFG. The flow within the glass capillary was produced by a computer-controlled infusion pump. In vivo, three consecutive LSFG scans were obtained in 20 eyes of 20 healthy Caucasian subjects before and after pharmacological pupil dilation. Relative flow volume (RFV), the primary output parameter of LSFG, was comparatively validated relative to absolute measurements of retinal blood flow and velocity as obtained from D-OCT. RESULTS: In the in vitro experiments, RFV was found to saturate at a level of approximately 700 arbitrary units (au) or 23.5 mm/s of actual velocity. In vivo, RFV was in significant agreement with absolute blood flow measurements as obtained from D-OCT in arteries (r = 0.69, P = 0.001) and veins (r = 0.74, P < 0.001). However, linear regression analysis revealed significant positive zero offset values for RFV of 223.4 and 282.7 au in arteries and veins, respectively. CONCLUSIONS: Measurements of RFV were successfully obtainable, reproducible, and not influenced by pharmacological pupil dilation. Nevertheless, our data revealed flaws in the LSFG method of measuring retinal perfusion in Caucasians. Adjustment to the technique is required to address apparent issues with RFV, especially saturation effects with higher arterial flow rates. The present dataset may provide a valuable tool to do so. (Clinicaltrials.gov number NCT02582411).
Authors: Seth W Holwerda; Randy H Kardon; Ryuya Hashimoto; Jan M Full; Julie K Nellis; Lyndsey E DuBose; Jess G Fiedorowicz; Gary L Pierce Journal: J Appl Physiol (1985) Date: 2020-05-21
Authors: Katarzyna J Witkowska; Ahmed M Bata; Giacomo Calzetti; Nikolaus Luft; Klemens Fondi; Piotr A Wozniak; Doreen Schmidl; Matthias Bolz; Alina Popa-Cherecheanu; René M Werkmeister; Gerhard Garhöfer; Leopold Schmetterer Journal: PLoS One Date: 2017-09-12 Impact factor: 3.240
Authors: Klemens Fondi; Ahmed M Bata; Nikolaus Luft; Katarzyna J Witkowska; René M Werkmeister; Doreen Schmidl; Matthias Bolz; Leopold Schmetterer; Gerhard Garhöfer Journal: PLoS One Date: 2018-11-28 Impact factor: 3.240
Authors: Giacomo Calzetti; Klemens Fondi; Ahmed M Bata; Nikolaus Luft; Piotr A Wozniak; Katarzyna J Witkowska; Matthias Bolz; Alina Popa-Cherecheanu; René M Werkmeister; Doreen Schmidl; Gerhard Garhöfer; Leopold Schmetterer Journal: Br J Ophthalmol Date: 2018-02-22 Impact factor: 4.638