Comparison between OCT B-Scan and En Face Imaging for the Diagnosis of Early Macular Atrophy in Age-Related Macular Degeneration

Abstract

Purpose : To determine the similarities between the grading of early atrophy on OCT B-scans with the grading of these lesions on en face OCT images from the same patient on the same day, we compared the gradings of complete retinal pigment epithelium and outer retinal atrophy (cRORA) and incomplete retinal pigment epithelium and outer retinal atrophy (iRORA) on B-scans with the grading of persistent choroidal hypertransmission defects (hyperTDs) on en face OCT images.

Methods : This retrospective study consisted of 19 eyes with late nonexudative AMD undergoing same day 6x6 mm macular scans using both SD-OCT (Spectralis® Heidelberg, 512x97, ART:9) and SS-OCTA (PLEX® Elite 9000, Carl Zeiss Meditec, 500x500 angio pattern) instruments. SS-OCTA and SD-OCT en face images were generated from a sub-retinal pigment epithelium slab positioned 64-400 μm below Bruch's membrane. Grading of cRORA and iRORA on SD-OCT B-scan images was performed using individual B-scans and then when looking at neighboring B-scans (+/-5) when performing the grading exercise.

Results : There was a high degree of agreement (99.6%) between the gradings of cRORA lesions and persistent hyperTDs. However, when using individual B-scans, 50% of iRORA lesions were found to be contained within persistent hyperTDs were cRORA when graded in a non-horizontal dimension. When neighboring B-scans were included in the B-scan grading, 27.4% of iRORA lesions were found to be contained within persistent hyperTDs and were cRORA when graded in a non-horizontal dimension.

Conclusions : While the horizontal B-scan diagnosis of cRORA and the en face diagnosis of persistent choroidal hyperTDs have an excellent agreement of 99.6%, the horizontal B-scan diagnosis of iRORA is frequently associated with persistent hyperTDs on en face imaging that have a non-horizontal dimension ≥ 250 µm suggesting the need to use en face images when grading cRORA or the need to include neighboring B-scans from dense raster scan patterns when grading the full extent of hyperTDs, but even after including the neighboring 5 B-scans, 27.4% of iRORA is cRORA on en face imaging.

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