Comparison between B-Scan and En Face Images for Incomplete and Complete Retinal Pigment Epithelium and Outer Retinal Atrophy

Abstract

To evaluate and compare the detection of incomplete and complete retinal pigment epithelium and outer retinal atrophy (iRORA and cRORA) assessed on optical coherence tomography (OCT) B-scans versus persistent choroidal hypertransmission defects (hyperTDs) assessed by en face choroidal OCT images. Retrospective, cross-sectional study. Patients with late atrophic age-related macular degeneration imaged on the same day using both Spectralis OCT and Cirrus OCT. Agreement between the B-scan and en face OCT for the detection of hyperTDs and cRORA and iRORA. Two independent graders examined en face OCT and structural OCT to determine the presence and location of hyperTDs, iRORA and cRORA. A total of 239 iRORA and cRORA lesions were detected on the B-scans, and 249 hyperTD lesions were identified on the en face OCT images. There was no significant difference (P = 0.881) in the number of lesions. There was no significant difference in the 134 cRORA lesions identified on B-scans and the 131 hyperTDs detected on en face OCT images (P = 0.125.) A total of 105 iRORA lesions were identified by B-scan assessment; however, 50 of these iRORA lesions met the criteria for a persistent hyperTDs on en face OCT images (P < 0.0001). When considering the topographic correspondence between B-scan and en face OCT detected lesions, the mean percentage of agreement between B-scan detection of cRORA lesions with en face OCT detection was 97.6 % (P=0.125). We observed an overall high agreement between cRORA lesions identified on B-scans and persistent hyperTDs identified on en face OCT. However, en face imaging was able to detect iRORA lesions that had a greatest linear dimension ≥ 250 μm in a non-horizontal en face dimension.