Repeatability of Choroidal Imaging Metrics in Handheld versus Tabletop OCT images in Adults

Abstract

Purpose : Few studies have looked at repeatability of the choroidal vascularity index (CVI) in different OCT imaging modalities. We performed a retrospective image analysis to compare a handheld swept-source research OCT system (UC3) to a gold standard tabletop commercial Spectralis OCT system.

Methods : A total of 10 healthy adults from ages 28-44 were imaged using Spectralis without Enhanced Depth Imaging (EDI) and UC3. Each adult had up to 12 images of the right eye obtained. Bruch’s membrane and choroidal-scleral junction (CSJ) were automatically segmented using a MATLAB software. Images were classified by a grader into three categories: clear CJS, poorly visible CSJ, and unclear CSJ. The CVI, stromal area (SA), luminal area (LA), and total choroidal area (TCA) in the 1.5mm sub-foveal region of choroid centered on the fovea were calculated using Image J by a single grader (Figure 1). Analysis of variance for each choroidal metric was performed to determine repeatability using standard deviation of repeatability (square root of residual variance), coefficient of variation (standard deviation for repeatability divided by mean of the specific choroidal metric of an image modality) and intraclass correlation coefficient (ICC). Analyses were performed for all images combined and then stratified by image quality.

Results : Choroidal metrics were calculated in 67 Spectralis images and 90 UC3 images, of which good quality images comprised 48% and 44% respectively. When all images were considered (Table 1), the coefficient of variation (COV) for repeatability for CVI was 2.13% for UC3 and 2.99% for Spectralis. The COV for SA, LA, and TCA were also lower (5.45-8.26%) in UC3 than Spectralis (8.00-12.01%). When stratified by image quality, the COV for repeatability for each choroidal metric was lower in clear CSJ images compared to poorly visible CSJ images for UC3 and Spectralis.

Conclusions : There is greater repeatability in UC3 compared to Spectralis (no EDI) across all four choroidal metrics. Within each system, there is greater repeatability for all four choroidal metrics in images with a clear CSJ when compared to images with a poorly visible CSJ. Image quality can be an important factor to consider when calculating choroidal metrics.

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

 

Figure 1: UC3 image with overlayed choroidal imaging metrics

 

Table 1: Repeatability of choroidal imaging metrics from UC3 and Spectralis in all images and stratified by image quality