Image Embossing Enhances Visualization of Retinal Pigmented Epithelium Alterations in Central Serous Chorioretinopathy

Abstract

Purpose : Central serous chorioretinopathy (CSCR) is a vision-threatening disease that 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 sharpness. In this retrospective, observational study, we explored how embossing to sharpen FAF images may improve RPE alteration identification in eyes with CSCR (Figure 1). Accuracy was determined based on Intraclass Correlation Coefficient (ICC) and RPE lesion area measurement.

Methods : This study includes 20 eyes of 16 patients with CSCR with RPE alterations on FAF confirmed by OCT and clinical examination. Exclusion criteria included poor image quality and presence of shadows. Images were embossed using the Pixelied website with a coefficient of 0.5. The area of RPE alteration was assessed by two masked, double-blinded observers (ImageJ Fiji software). Significance was evaluated using paired t-test. ICC was used to determine the consistency between observers to determine whether accuracy, via inter-rater agreement, is greater before or after embossing.

Results : The mean age of the 16 patients was 50.3 ± 12.4 years. There were five females (31.25%) and 11 males (68.75%). The ICC for pre- and post-embossed images was 94.6% and 99.7%, respectively. The mean area of RPE alterations, which showed mottled appearance in both FAF and embossed processed images, were 109500.75 ± 97957.93 and 105951.95 ± 209290.31 before embossing, and 118693.7 ± 218354.21 and 119133.7 ± 221519.35 after embossing, with a P-value of 0.09. The two observers agreed on post-analysis questionnaire that RPE lesions were more visible, with a sharper border and better contrast in embossed images.

Conclusions : Embossing FAF images can enhance the visibility of the area of RPE alterations in CSCR patients, which allows for better accuracy in the measurement of these lesions, as indicated by improved ICC in embossed images. This technique can be a useful tool for better assessment of the RPE changes area and progression of CSCR patients during follow up.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

This image depicts FAF images of the right eye of a 47-year-old man with CSCR. The FAF (A) showed an area of mottled autofluorescence in the macula. Embossed image (B) exemplifies added depth. Pre- (C) and post-emboss (D) images were marked to measure RPE alteration area.