Repeatability of choroidal thickness measurements on Enhanced Depth Imaging OCT using different posterior boundaries

Abstract

Purpose : Variability in choroidal thickness (CT) measurements may be attributed to different definitions of the choroidal-scleral junction (CSJ) as the posterior boundary. To improve the accuracy of CT measurements, we investigated the repeatability of CT measurements with three different posterior boundary definitions using enhanced-depth imaging optical coherence tomography (EDI-OCT).

Methods : EDI-OCT images obtained from 91 normal eyes from 91 adults were evaluated. Two trained graders independently marked the CSJ using three different posterior boundaries: (1) the outer border of the choroidal vessel lumen (vascular choroidal thickness, VCT), (2) the outer border of the choroid stroma (stromal choroidal thickness, SCT), and (3) the inner border of the sclera (total choroidal thickness, TCT). CT measurements were taken at the fovea and at 0.5mm intervals up to 1.5mm nasal and temporal to the fovea, and averaged across the central 3mm (AvgCT). Interclass correlation coefficient (ICC) and coefficient of reliability (CR) were conducted to analyze both intergrader and intragrader reliability.

Results : The mean age of subjects was 56.77 ± 17.58 years. The mean CT at the fovea was 237.07 ± 84.85 for VCT, 293.27 ± 97.98 for SCT and 315.06 ± 95.42 for TCT. The mean AvgCT was 232.13 ± 75.22 for VCT, 286.97 ± 96.15 for SCT and 306.92 ± 92.63 for TCT. Intergrader (ICC 0.877–0.957) and intragrader (ICC 0.909–0.979) repeatability for CT measurements were excellent using all 3 boundaries. ICCs were generally greater for TCT (0.909–0.979) and SCT (0.898–0.978) than VCT (0.882–0.979); and for average CT measurements (0.922–0.979) than single-point CT measurements (0.877–0.978). Intergrader CR ranged from ±61.88 to ±117.40, while intragrader CR ranged from ±52.62 to ±103.17. The suprachoroidal layer (SCL) was visible in 15.38% of subjects.

Conclusions : CT measurements using all three CSJ boundaries demonstrate good intergrader and intragrader reliability. CT measured to the sclera (TCT) may be more reproducible than CT measurements based on the choroid stroma (SCT) or choroidal vessel lumen (VCT). Average CT may be more reliable than individual points.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

(A) EDI-OCT image shows a CSJ with visible SCL and the different posterior boundaries for measuring CT. Semi-automated segmentation lines of VCT (B), SCT (C), and TCT (D) as well as the outer border of the retinal pigmented layer (yellow) are shown.