Purpose: To evaluate the repeatability and reproducibility of manual choroidal volume (CV) measurements by spectral domain- optical coherence tomography (SD-OCT) using enhanced depth imaging (EDI).
Methods: Sixty eyes of 32 patients with or without any ocular chorioretinal diseases were enrolled prospectively. Thirty-one choroidal scans were performed on each eye, centered at the fovea, using a raster protocol. Two masked observers demarcated choroidal boundaries by using built-in automated retinal segmentation software on two separate sessions. Observers were masked to each other's and their own previous readings. A standardized grid centered on the fovea was positioned automatically by OCT software, and values for average CVs and total CVs in three concentric rings were noted. The agreement between the intraobserver measurements or interobserver measurements was assessed using the concordance correlation coefficient (CCC). Bland-Altman plots were used to assess the clinically relevant magnitude of differences between inter- and intraobserver measurements.
Results: The interobserver CCC for the overall average CV was very high, 0.9956 (95% confidence interval [CI], 0.991-0.9968). CCCs for all three Early Treatment Diabetic Retinopathy Study concentric rings between two graders was 0.98 to 0.99 (95% CI, 0.97-0.98). Similarly intraobserver repeatability of two graders also ranged from 0.98 to 0.99. The interobserver coefficient of reproducibility was approximately 0.42 (95% CI, 0.34-0.5 mm(3)) for the average CV.
Conclusions: CV measurement by manual segmentation using built-in automated retinal segmentation software on EDI-SD-OCT is highly reproducible and repeatable and has a very small range of variability.