Comparison between en face structural spectral-domain and swept-source OCT for the detection of hyperpigmentation in AMD

Abstract

Purpose : An algorithm developed for swept-source OCT angiography (SS-OCTA) scan pattern was used on spectral-domain OCT angiography (SD-OCTA) scans to determine if both OCT modalities yield similar results for the measurement of hyperpigmentation in eyes with intermediate age-related macular degeneration (iAMD).

Methods : In this retrospective review of subjects enrolled in a prospective SS-OCT and SD-OCT study, both SD-OCTA and SS-OCTA imaging were performed at the same visit using the 6x6mm scan patterns. Hyperpigmentation (hyperPig) was defined and detected as hypotransmission defects (hypoTDs) on en face structural images generated from a custom slab positioned 64 to 400 µm beneath Bruch’s membrane and confirmed by the presence of hyperreflective foci (HRF) and/or foci of thickened RPE on corresponding B-scans as previously published. Two graders independently validated the hyperpigmented lesions and used a published semiautomated algorithm previously developed for SS-OCTA scans to generate outlines of the lesions for both scan modalities. The total area of the hyperpigmented lesions within the 5mm circle centered on the fovea was measured using each imaging method. The means of the square root (sqrt) area measurents were compared.

Results : A total of 40 eyes from 35 patients were compared. The sqrt total pigment area from both imaging modalities were highly correlated, with a concordance correlation coefficient (CCC) of 0.94 (95% CI: 0.88 to 0.97; p < 0.001; Figure 1). The mean sqrt of the total pigment area identified using SS-OCTA imaging was 0.391 (SD: 0.170) and 0.394 (SD: 0.187) using SD-OCTA imaging, with a mean difference of -0.003 (95% CI: -0.022 to 0.016; p = 0.78; Figure 1). The small differences between the scans were not statistically nor clinically significant (Figure 2).

Conclusions : SD-OCTA scans provide similar results to SS-OCTA scans when used to identify and measure the total hyperPig burden by using a semiautomated algorithm previously developed for SS-OCTA. These results suggest that either a 6x6mm SD-OCTA or a SS-OCTA scan pattern can be used to determine the total macular hyperPig burden in eyes with AMD.

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