Abstract
Purpose :
To analyze and compare grading of diabetic retinopathy (DR) severity level using standard 30° ETDRS 7-field photography and CLARUS 500 ultra-widefield imaging system.
Methods :
A cross-sectional analysis of retinal images of patients with type 2 diabetes (n=123 eyes) was performed. All patients underwent 7-field color fundus photography (CFP) at 30° on a standard Topcon TRX-50DR® camera and ultra-widefield (UWF) imaging at 135° on a CLARUS™ 500 (ZEISS, Dublin, CA, USA) by an automatic montage of two 90° images (nasal and temporal). 7-field photographs were graded by two graders, according to the Early Treatment Diabetic Retinopathy Study (ETDRS). For CLARUS UWF images, a 7-field grid was applied using prototype CLARUS software, and the same ETDRS grading procedures were performed inside that area only. Grading of DR severity level was compared between these two methods to evaluate the agreement between both imaging techniques.
Results :
Images of 123 eyes from 63 diabetic patients were considered for analysis. According to the 7-field 30° images, 14 eyes were considered DR severity level 10-20, 58 eyes were considered level 35, 31 eyes level 43, 14 eyes level 47, 5 eyes level 53 and 1 eye level 61. The same DR severity level was achieved with CLARUS 500 UWF images in 56% of the cases. However, 44 eyes (36%) showed a worse DR level with UWF images, mostly due to a better visualization of haemorrhages and a higher detection of intraretinal microvascular abnormalities (IRMA). Only 8% (n=10) of the cases showed a decrease in severity level with CLARUS 500 system, mainly due to the presence of artifacts in the montage junctions of the 2 images (blurred zones) and presence of cortical cataracts.
Conclusions :
The UWF CLARUS 500 system showed a considerable agreement with standard 30° 7-field CFP in all ETDRS levels in images with unambiguous structures. Moreover, CLARUS images showed an improved ability to detect IRMA and to evaluate hemorrhage severity demonstrating that one UWF photograph can be used to grade ETDRS severity level more accurately owing to a more efficient workflow with overall superior image quality and visualization.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.