Visualization of the Persistent Avascular Retina in Ultra-widefield Fundus Imaging Using a Digital Green Filter

AbstractPurpose The aim of this study was to determine which filter facilitated the easier detection of the persistent avascular retina (PAR) in ultra-widefield (UWF) fundus imaging in children undergoing retinopathy of prematurity (ROP). Methods A total of 20 eyes of 10 children aged between 6 to 9 who underwent diagnostic and therapeutic procedures for ROP were included. Fundus images were obtained using Optos confocal scanning laser ophthalmoscopy (cSLO; Optos PLC, Dunfermline, Scotland). The images were divided and recorded into three groups as original images (composite filter), red filter, and green filter. These images were prepared as a slideshow for 10 ophthalmology specialists and they were surveyed to determine in which filter the peripheral avascular area was more easily detected. The results were evaluated. Results The rate of detecting the PAR in green-filtered images by the participants included in the study was found to be statistically higher compared to other filters (composite 0,63 ± 0,09 (0,5 − 0,8), red 0,12 ± 0,05 (0,05 − 0,2), and green 0,94 ± 0,06 (0,85 − 1), p < 0.0001). All respondents reported that the boundaries of the peripheral avascular area were more clearly defined in the green-filtered UWF fundus images. Conclusion Each filters used in UWF fundus imaging helps to visualize different layers of the retina. Our study results showed that the green filter, by overshadowing the choroidal vessels, made the retinal vessel terminations more prominent. Based on these findings, we believe that UWF fundus images with the green filter selected are more useful for detecting and monitoring the PAR.