Purpose: To develop a new method to quantify the choroidal vessel density by binarizing ultra-wide-field indocyanine green angiography (ICGA) images and determine whether values are altered in diseased eyes.
Design: Reliability and validity analysis.
Methods: Ultra-wide-field fluorescein angiography (FA) and ICGA images were obtained using an ultra-wide-field imaging device (Optos California ultra-wide-field imaging device; Dunfermline, Scotland, UK) in 11 eyes of 11 patients without chorioretinal diseases. The angiographic signals of the choroidal vessels were determined by subtracting those of the retinal vasculature and optic disc on the FA images from the ICGA images, binarized by Niblack's method, and the choroidal vessel density calculated. Reproducibility of the method was assessed by calculating the coefficient of variance, coefficient of repeatability, and intraclass correlation coefficient. The relationships between age, spherical equivalent refractive error (SERE), and intraocular pressure and the vasculature density were assessed. To investigate possible impacts of chorioretinal diseases on the vasculature density, 10 eyes of 7 patients with central serous chorioretinopathy (CSC) were compared with the 11 control eyes.
Results: Choroidal vessels were contrasted by binarizing ICGA images. The method to quantify the choroidal vessel density showed high reproducibility. The SERE was correlated significantly (r = 0.573, P < .05) with the vasculature density. In the 11 control eyes, the vasculature density was 34.26% ± 0.77% in the entire area, 31.37% ± 0.97% in the superior portion, 36.98% ± 0.88% in the inferior portion, 37.01% ± 1.44% in the posterior portion, and 34.17% ± 0.77% in the peripheral portion. In eyes with CSC, the density was significantly (P < .05) higher: 36.46% ± 0.49%, 34.02% ± 0.97%, 38.65% ± 0.27%, 41.04% ± 0.82%, and 36.36% ± 0.51%, respectively.
Conclusions: Binarization of ultra-wide-field ICGA images enabled quantification of the choroidal vessel density, which was altered in eyes with CSC. This method of measuring the choroidal vessel density may provide new insights into diagnosing and treating chorioretinal diseases.
Copyright © 2016 Elsevier Inc. All rights reserved.