Embossing enhances visualization of retinal pigment epithelium alterations in fundus autofluorescence in central serous chorioretinopathy

PurposeCentral serous chorioretinopathy (CSCR) demonstrates retinal pigment epithelium (RPE) alterations visible on fundus autofluorescence (FAF). Embossing is an image processing technique that replaces pixels with a shadow or a highlight, improving image visualization. We explored how embossing improves the delineation of altered RPE areas in eyes with chronic CSCR on blue-FAF images.MethodsThis study includes 52 eyes of 40 patients with chronic CSCR. Images were embossed with a coefficient of 0.5. The area of RPE alteration was assessed by two masked, double-blinded observers using ImageJ Fiji software. Accuracy was assessed based on inter-rater reliability (ICC) and compared before and after embossing using Fisher's z-transformation.ResultsThe mean age of the study patients was 53.02 ± 12.87 years. The RPE alteration area measurements by the first observer for the pre-embossed images was 12.1 ± 13.1 mm2, and for the post-embossed images was 11.9 ± 13.4 mm2 (<i>P</i> = 0.7). The RPE alteration area measurements by the second observer for the pre-embossed images was 11.3 ± 13.3 mm2, and for the post-embossed images was 10.3 ± 12.8 mm2 (<i>P</i> = 0.5). The mean area for both observers in the pre-embossed images was 11.7 ± 12.8 mm2, and in the post-embossed images was 11.1 ± 13.0 mm2 (<i>P</i> = 0.217). The ICC in the pre-embossed images between two observers was 0.931 (CI 0.879-0.960), which increased to 0.983 (CI 0.970-0.990) in post-embossed images (<i>P</i> < 0.001).ConclusionsEmbossing FAF images can enhance the visibility of RPE alterations in CSCR, allowing for better delineation of borders, which improves accuracy.