Comparison Between Optical Coherence Tomography B-scan and En Face Imaging for the Diagnosis of Early Macular Atrophy in Age-Related Macular Degeneration.

PURPOSE

The gradings of complete retinal pigment epithelium (RPE) and outer retinal atrophy (cRORA) and incomplete RPE and outer retinal atrophy (iRORA) on spectral domain optical coherence tomography (SD-OCT) B-scans were compared with the grading of persistent choroidal hypertransmission defects (hyperTDs) on swept-source optical coherence tomography angiography (SS-OCTA) en face images.

DESIGN

Comparative diagnostic analysis of prospective study data.

METHODS

Patients with late nonexudative age-related macular degeneration underwent same-day 6×6-mm macular scans using both SD-OCT (Spectralis Heidelberg, 512×97, automatic real-time tracking: 9) and SS-OCTA (PLEX Elite 9000, Carl Zeiss Meditec, 500×500 angio pattern) instruments. SS-OCTA and SD-OCT en face images were generated from a sub-RPE slab positioned 64 to 400 µm below Bruch's membrane. SD-OCT B-scan gradings, which included an inspection of neighboring B-scans for the diagnosis of cRORA and iRORA, were performed at the Moran Eye Center, and gradings of en face images to identify persistent choroidal hyperTDs were performed at the Bascom Palmer Eye Institute and Tel Aviv Medical Center.

RESULTS

There was a high degree of agreement (99.6%) between the gradings of cRORA lesions and persistent hyperTDs. However, 27.4% of iRORA lesions were found to be contained within persistent hyperTDs. This discrepancy was due to the finding that 27.5% of iRORA lesions were diagnosed as having a greatest linear horizontal dimension of <250 µm on B-scans, but on en face images, these B-scan-defined iRORA lesions were found to have the greatest linear dimensions in the nonhorizontal dimension that were ≥250 µm.

CONCLUSIONS

This report demonstrates the benefits of using en face OCT imaging to identify cRORA lesions and highlights the need to acquire dense raster B-scans with the grading neighboring B-scans when identifying iRORA lesions to assess the full extent of the iRORA lesions in the nonhorizontal dimension. Although neighboring B-scans were inspected, 27.5% of iRORA lesions were actually part of larger cRORA lesions when graded using an en face strategy.