Imaging of choroidal hemodynamics in eyes with polypoidal choroidal vasculopathy using laser speckle phenomenon

Abstract

To compare the images of choroidal vasculature obtained by laser speckle flowgraphy (LSFG) and indocyanine green angiography (IA), and to evaluate the imaging of choroidal hemodynamics in eyes with polypoidal choroidal vasculopathy (PCV) using LSFG. We performed IA and wide-field LSFG, which measures the index of blood velocity (mean square blur rate; MBR) in 25 eyes with PCV. We constructed an MBR map of the sequential MBR images (600 x 280 pixels) from four or five pulsations during measurement (4.5 s). A grayscale composite map of a still image was obtained by averaging the cumulative sum of the MBR map. We compared the angiographic images of the grayscale composite map to IA results and evaluated the choroidal hemodynamics of 25 eyes with PCV in the MBR map. The choroidal vasculature on the grayscale map had a resolution similar to the IA results. The grayscale map detected branching network vessels in 20 (80%) of the 25 eyes and polypoidal lesions in 11 (44%) eyes. The MBR map showed that the pulsations of the branching network vessels and polypoidal lesions were synchronized with the cardiac rhythm. The fluctuation rates of the PCV lesions during one pulsation ranged from 8.3% to 26.7% (mean, 13.6%) and from 7.3% to 24.6% (mean, 15.9%) for the intact choroid. The MBR map showed the watershed zone and highest signal intensity in the macula. Using an MBR map, wide-field LSFG revealed the pulsating choroidal hemodynamics of the posterior fundus. A grayscale composite map showed the fine choroidal vasculature whose resolution was comparable to that of IA. The branching network vessels of PCV showed that pulsation was synchronized with the choroidal vessels. Wide-field LSFG showed the highest choroidal blood flow in the macular area and the presence of a watershed zone.