Kristi Dohm, Nancy Barrett, Kyle McDaniel, Barbara Blodi, Amitha Domalpally

Abstract

Purpose: Diabetic retinopathy has traditionally been evaluated using the Early Treatment Diabetic Retinopathy Severity Scale (ETDRS) from 7-field (7F) stereoscopic color photographs and is considered the gold standard. Ultrawide field color (UWF-C) imaging has recently become available for viewing a wider area of the retina. We assessed DR severity level from standard 7-field images and compared them to the 7-field area equivalent of the UWF-C images.

Methods: DR severity was determined using ETDRS 12 step scale from both 7F and UWF-C images. A grid outlining the 7F area of the UWF-C was centered on the image with peripheral areas masked (masked grid, figure). The ETDRS level that was determined using this grid was called the UWF 7F DR level. The ETDRS level that was determined using standard 7F images was called 7F DR level. All images were evaluated independently using double read with adjudication.

Results: Of the 152 pairs of images evaluated, 7F DR level was ungradable in 3 (1.9%) of 7F images and could not be assessed in 17 (11.2%) of UWF-C images. Of the 133 pairs of gradable images, the 7F DR level was well distributed with 13 (9.8%) showing no or early DR, 44 (33.1%) with mild-moderate non-proliferative DR, 55 (41.4%) with moderately severe – severe non-proliferative DR, and 21 (15.8%) with proliferative DR. Comparing 7F DR level to UWF 7F DR level (masked grid), agreement was exact in 47.0 % of the eyes and within 1 step in 84.2 % (weighted kappa 0.59 [SE 0.05]). Of the 70 eyes with disagreement between DR levels, 41 (58.6%) were due to a lower grade assessment in UWF DR level compared to 7F DR level.

Conclusion: The study shows moderate agreement between DR levels determined within standard 7F imaging and UWF-C images. The ungradable rate is higher with UWF-C images. In eyes with disagreement on DR level, tThe ETDRS level is subject to undercallingmore likely to be lower with UWF-C images; this is potentially due to difficulty in visualizing of intraretinal microvascular abnormalities (IRMA) with UWF-C images.