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. 2018 Mar 2;8:3916. doi: 10.1038/s41598-018-22251-7

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© The Author(s) 2018

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

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Computation of avascular zones. (A) Vasculature skeleton and avascular regions, defined as 8-connected background objects within the circular region of interest (red circle), displayed in random colours for better visibility. (B) Grey-scale-coded distance to the closest skeleton pixel. Cyan contours indicate regions enclosing pixels which maximal distance to the skeleton is larger than 1% of Φ_retina. Remaining avascular regions are contoured in red. (C) Resulting avascular region overlapped with original image. (D) Avascular area computed by QuRVA (red) and manual segmentations (shades of green), for each image of the image set. Note that the value of the automatic algorithm lies within the range of manual segmentations for the vast majority of the images. (E) Percent fraction of retinal pixels that are either false positive or false negative, according to the consensus of manual evaluators, for all images and grouped by user. Arrows indicate the median value across images for each evaluator, and the dashed red line indicates the median error for QuRVA, which is similar to manuals.