Figure 3
Quantification of retinal hemorrhagic patterns at the posterior pole of eyes with acute branch retinal vein occlusion using the parallelism method.
Images of the posterior pole of an eye with a typical flame-shaped retinal hemorrhage (A–D) and of an eye with a non-flame-shaped blot retinal hemorrhage (E–H) are shown. Optos color fundus photographs (A,E), the split green channel of the originals (B,F), extracted skeletonized images of the retinal hemorrhage (C,G) and hemorrhage-sparse areas (D,H) are shown. The skeletonized images are made by applying a filter using ImageJ software followed by binarization with Otsu’s thresholding method. The parallelism values are then calculated based on the processed images. Parallelism is expected to show higher values in eyes with a flame-shaped retinal hemorrhage and lower values in eyes with a non-flame-shaped dot or blot retinal hemorrhage. The averaged parallelism values are 0.496 [(0.590 + 0.402)/2] in an eye with a flame-shaped retinal hemorrhage (C,D) and 0.084 [(0.062 + 0.106)/2)] in an eye with a non-flame-shaped blot retinal hemorrhage (G,H).
