Measuring retinal blood flow in rats using Doppler optical coherence tomography without knowing eyeball axial length. Issue 9 (19th August 2015)

• Record Type: Journal Article
• Authors: Liu, Wenzhong; Yi, Ji; Chen, Siyu; Jiao, Shuliang; Zhang, Hao F.
• Is Part Of: Medical physics. Volume 42:Issue 9(2015)
• Page Start: 5356
• Page End: 5362
• Publication Date: 2015-08-19
• Subjects: blood flow measurement -- Doppler measurement -- eye -- optical tomography -- phantoms; Visual imaging -- Hemodynamics; Measuring blood flow -- Biological material, e.g. blood, urine; Haemocytometers; Doppler optical coherence tomography -- retinal blood flow -- eyeball axial length -- dual‐ring scanning; Haemodynamics -- Doppler effect -- Blood flow measurement -- Flow rate measurement -- Optical coherence tomography -- Retina -- Velocity measurement -- Flow visualization; Medical physics -- Periodicals; Medical physics; Geneeskunde; Natuurkunde; Toepassingen; Biophysics; Periodicals; Periodicals; Electronic journals; 610.153
• DOI: 10.1118/1.4928597
• Languages: English
• ISSNs: 0094-2405

Abstract

Abstract : Purpose: Doppler optical coherence tomography (OCT) is widely used for measuring retinal blood flow. Existing Doppler OCT methods require the eyeball axial length, in which empirical values are usually used. However, variations in the axial length can create a bias unaccounted for in the retinal blood flow measurement. The authors plan to develop a Doppler OCT method that can measure the total retinal blood flow rate without requiring the eyeball axial length. Methods: The authors measured the retinal blood flow rate using a dual‐ring scanning protocol. The small and large scanning rings entered the eye at different incident angles (small ring: 4°; large ring: 6°), focused on different locations on the retina, and detected the projected velocities/phase shifts along the probing beams. The authors calculated the ratio of the projected velocities between the two rings, and then used this ratio to estimate absolute flow velocity. The authors tested this method in both Intralipid phantoms and in vivo rats. Results: In the Intralipid flow phantom experiments, the preset and measured flow rates were consistent with the coefficient of determination as 0.97. Linear fitting between preset and measured flow rates determined the fitting slope as 1.07 and the intercept as −0.28. In in vivo rat experiments, the measured average total retinal blood flow was 7.02 ± 0.31 μ l/min among four wild‐type rats. The authors' measured flow rates were consistent with results in the literature. Conclusions: By using a dual‐ring scanning protocol with carefully controlled incident angle difference between the two scanning rings in Doppler OCT, the authors demonstrated that it is feasible to measure the absolute retinal blood flow without knowing the eyeball axial length.