Widefield choroidal thickness measurement comparison between manual and multilayer segmentation

Abstract

Purpose : Segmentation of the choroid layer in optical coherence tomography (OCT) remains valuable for the analysis of retinal diseases. This study utilizes a multilayer segmentation (MLS) algorithm (Luis De Sisternes, et al, IOVS July 2018, Vol.59, 1512) to assess its performance in comparison to manual choroidal segmentation in terms of choroidal thickness measurements.

Methods : 25 scans from 14 patients (one or both eyes) with a variety of retinal diseases were collected by using PLEX® Elite 9000 (ZEISS, Dublin, CA) swept-source OCT (SS-OCT) with a scan pattern of Angio (15mm x15mm) (834 x 834 x 3072 pixels). Choroidal thickness maps (CTMs) were generated and defined as the distance between Bruch's membrane (BM) and the choroidal-scleral junction (CSJ) (as depicted in Figure 1). In comparison, manual segmentation of BM and CSJ was performed by human graders. The CTMs generated through manual segmentation were compared to those by the MLS algorithm. The performance of the algorithm was evaluated using the correlation between manual and automated methods for each subfield of the expanded ETDRS grid (Figure 2). Regression plots of the various fields within the ETDRS grid were also reported.

Results : Figure 2 shows the ETDRS grid and the correlation of CTMs of 25 scans between manual and MLS. A strong correlation (>0.95) was found between manual and automated measurements for all subfields within the ETDRS grid. Overall, the MLS method demonstrated good performance compared to manual segmentation across the entire field.

Conclusions : In this study, we compared CTMs generated by manual and automated MLS methods. The results showed a strong correlation between the EDTRS subfields calculated by MLS and manual measurements. MLS could be utilized for automatic analysis of widefield choroidal thickness and provide valuable diagnostic insights for retinal diseases.

This abstract was presented at the 2023 ARVO Imaging in the Eye Conference, held in New Orleans, LA, April 21-22, 2023.

 

Figure 1: Examples of choroidal segmentation generated through MLS (solid green line) and manual (dashed red line) methods in two representative eyes.

 

Figure 2: a) ETDRS zones and correlations (r) between Manual and MLS and b) regression plots for each ETDRS grid zone (units are in microns).