Abstract
Spectral-domain OCT angiography (SD-OCTA) scans were tested in an algorithm developed for use with swept-source OCT angiography (SS-OCTA) scans to determine if SD-OCTA scans yielded similar results for the detection and measurement of persistent choroidal hypertransmission defects (hyperTDs).
Retrospective Study
Forty pairs of scans from 32 patients with late stage nonexudative age-related macular degeneration (AMD)
Patients underwent both SD-OCTA and SS-OCTA imaging at the same visit using the 6x6 mm OCTA scan patterns. Using a semiautomatic algorithm that helped with outlining the hyperTDs, two graders independently validated persistent hyperTDs, which are defined as having a greatest linear dimension ≥ 250 μm on the en face images generated using a slab extending from 64 to 400 μm beneath Bruch’s membrane. The number of lesions and square root (sqrt) total area of the hyperTDs were obtained from the algorithm using each imaging method.
The mean sqrt area measurements and the number of hyperTDs were compared.
The number of lesions and sqrt total area of the hyperTDs were highly concordant between the two instruments (rc = 0.969, rc = 0.999, respectively). The mean number of hyperTDs were 4.3 ± 3.1 for SD-OCTA scans and 4.5 ± 3.3 for SS-OCTA scans (p=0.06). The mean sqrt total area measurements were 1.16 ± 0.64 mm for the SD-OCTA scans and 1.17 ± 0.65 mm for SS-OCTA scans (p <0.001). Due to the small standard error of the differences, the mean difference between the scans was statistically significant, but not clinically significant.
SD-OCTA scans provide similar results to SS-OCTA scans when used to obtain the number and area measurements of persistent hyperTDs through a semiautomated algorithm previously developed for SS-OCTA. This facilitates the detection of atrophy with a more widely available scan pattern and the longitudinal study of early to late-stage AMD.