Table 5. Image binarization protocol in Sonoda et al. vs current study.

	Sonoda et al. (2014)30	Sonoda et al. (2015)31	Current study
Study sample size	15 eyes of 15 subjects	180 eyes of 180 subjects	345 eyes of 345 subjects
Choroidal area measured	1.5 mm	7.5 mm	1.5 mm
Location of measurement	Centered on fovea, 1500 um	Entire raster scan, 7500 um	Centered on fovea (1500 um) due to the segmental nature of choroidal blood supply as described by Hayreh et al.37
Pre-selection of vessels	3 choroidal vessels with lumens >100 mm were randomly selected and the average reflectivity of these areas was determined by the software		Used autolocal threshold techniques to allow binarization of smaller choroidal vessels or choriocapillaris.
Brightness adjustment	Average brightness was set as the minimum value		Brightness was not adjusted as it would reduce the contrast between luminal and stromal areas and possibly affect the autolocal threshold.
Order of binarization	Region of interest selected prior to image binarization		To get a clear view of the choroid-scleral interface, image binarization was performed prior to area selection.
Image segmentation time	~5 minutes per image		~1 minute per image