Repeatability of Optical Coherence Tomography Angiography in Uveitic Eyes

To investigate the intravisit repeatability of optical coherence tomography angiography (OCTA) in a cohort of uveitis patients.

One hundred ten patients were imaged twice per eye, per visit, using the Zeiss Cirrus HD-OCT Model 5000 device. To calculate choriocapillaris flow void area (CC FV) 6 × 6-mm images were used, and 3 × 3-mm images were used to calculate vessel density (VD) and the foveal avascular zone area (FAZ) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP). Repeatability was measured using Bland-Altman analyses and intraclass correlation coefficients (ICC) with associated coefficient of variation (CV).

The level of intravisit repeatability differed across indices ranging from moderate to excellent. CC FV had the highest intravisit repeatability with an ICC of 0.980 (95%CI, 0.966-0.989), a CV of 15.9% and Bland-Altman limits of agreement from -0.398 to 0.411 mm². DCP FAZ had the lowest intravisit repeatability with an ICC of 0.677 (95%CI, 0.510-0.796), a CV of 17.4% and Bland-Altman limits of agreement from -0.395 to -0.355 mm². Intraoperator repeatability was excellent across all indices.

This study demonstrates that OCTA is a reliable tool to quantitatively assess specific indices of vascular structure in uveitis patients with good intravisit repeatability. However, the range of variability for each index should be taken into account when evaluating clinically meaningful changes.

The repeatability of the metrics we have described has implications in supporting the development of OCTA-derived quantitative assessments of the retinal and choroidal vasculature in uveitis patients as potential imaging biomarkers.