Spectral-domain and swept-source OCT angiographic scans yield similar drusen measurements when processed with the same algorithm

Abstract

Purpose : To determine if SD-OCTA scans provide similar structural information as SS-OCTA scans from patients with intermediate age-related macular degeneration (iAMD), we compared drusen measurements from spectral-domain OCT angiography (SD-OCTA) and swept-source OCT angiography (SS-OCTA) scans obtained by using the same automated algorithm that had been developed and validated for SS-OCTA scans.

Methods : In this retrospective cohort study, patients with iAMD and drusen underwent both SD-OCTA and SS-OCTA imaging at the same visit using the 6X6 mm scan patterns. The SD-OCTA scan pattern consisted of 350 A-scans per B-scans with 350 B-scans along the y-axis with each B-scan repeated twice at each position. The SS-OCTA scan pattern consisted of 500 A-scans per B-scans with 500 B-scans along the y-axis with each B-scan repeated twice at each position. Using the same algorithm for the two instruments, we compared the square root (sqrt) area and cube root (cbrt) volume measurements within both 3 mm and 5 mm fovea-centered circles using paired t-tests.

Results : 40 eyes from 22 subjects imaged between April 2021 to August 2022 were included in this study. In the 3 mm circle, mean drusen area values were 1.58 ± 0.57 mm and 1.49 ± 0.58 mm from SD-OCTA and SS-OCTA scans, respectively. In the 5 mm circle, mean drusen area values were 1.88 ± 0.59 mm and 1.76 ± 0.58 mm from SD-OCTA and SS-OCTA scans, respectively. In the 3 mm circle, mean drusen volume values were 0.54 ± 0.19 mm and 0.51 ± 0.20 mm from SD-OCTA and SS-OCTA scans, respectively. In the 5 mm circle, mean drusen volume values were 0.60 ± 0.17 mm and 0.57 ± 0.17 mm from SD-OCTA and SS-OCTA scans, respectively. There were small differences in mean sqrt drusen area and cbrt drusen volume measurements between the two instruments (all P<0.001) with SD-OCTA scans resulting in slightly larger values than those from SS-OCTA scans due to slight differences in retinal pigment epithelium (RPE) segmentation. However, correlations between SS-OCTA and SD-OCTA measurements were very strong (all coefficients ≥ 0.98; all P<0.001).

Conclusions : SD-OCTA scans provide accurate structural information, such as drusen area and volume measurements, as well as angiographic information so a single SD-OCTA scan should be sufficient when imaging most AMD patients.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.