Comparison of 7M, Clarus, and Optos Ultrawide Field Imaging Systems for Diabetic Retinopathy Assessment

Abstract

Purpose : Advances in ultrawide-field color (UWF-C) imaging technology have enabled visualization of the entire retina. This study aims to determine whether diabetic retinopathy (DR) assessment with UWF-C imaging is comparable with the current gold standard, standard 7-field (Std 7F) imaging for both the Clarus and the Optos cameras.

Methods : Participants had retinal color images taken using Std 7F imaging, Clarus, and Optos UWF-C imaging systems. DR severity scale (DRSS) was determined for the 7F area of each image set using the Early Treatment Diabetic Retinopathy Scale (ETDRS) 12-step scale. An additional global DR severity level was assigned for each UWF-C image set using the entire visible retina. Two graders assessed all images independently with adjudication by a third grader when agreement was not exact. There was a washout period of two days between grading each modality for the same patient.

Results : 50 eyes from 30 participants were evaluated. The 7F DR level was ungradable for 2 (4.0%) Std 7F image sets, 1 (2.0%) Clarus images, and 0 (0.0%) Optos images. Global DR level could not be assessed in 1 (2.0%) Clarus image set and 1 (2.0%) Optos image set. Comparing 7F DR levels between Std 7F and Clarus, agreement was exact in 55.0% of the eyes, within one step in 93.6% of the eyes, and within 2 steps in 100% of the eyes (wκ = 0.74). Comparing 7F DR levels between Std 7F and Optos, the results were 54.0%, 81.2%, and 89.6% respectively (wκ = 0.56). The results of Clarus Global relative to Optos Global were 56.0%, 87.5%, and 93.8% (wκ = 0.68) respectively. In eyes identified to have PDR on Stad 7F, disagreement was found in 1 eye with Clarus and 7 eyes with Optos imaging. Intergrader agreement for 7F ETDRS level was within 2 steps 100.0% of the time for 7F, 97.8% of the time for Clarus, and 92.0% of the time for Optos.

Conclusions : When comparing the DR levels determined within the 7F and global areas, our study found exact agreement between Std 7F and both UWF-C modalities in about half of all images. The majority of all eyes showed agreement within 1 step. These ranges of agreement may support UWF-C imaging as being comparable to Std 7F imaging for the assessment of DR severity.

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