Accuracy of digital images for assessing diabetic retinopathy

Abstract

Background: To determine the accuracy of diabetic retinopathy status assessments with and without pupil dilation using digital fundus photographs acquired by a clinic staff person and interpreted remotely by ophthalmologists. Method: Using early treatment diabetic retinopathy study (EDTRS) grading criteria, diabetic retinopathy status assessments were made by an experienced (nonphysician) retinal grader (NPG) based on seven standard feld 35-mm stereoscopic slides acquired by an experienced ophthalmic photographer. These assessments were compared with those of the same eyes made by two ophthalmologists and the NPG using digital photographs acquired by a clinic staff person using a high-resolution (800 × 600) digital color camera system. Results: Based on 35-mm slides, 38% of 244 diabetic patients had ETDRS =35 in at least one eye and 5% had visionthreatening diabetic retinopathy (ETDRS =53 or macular edema). The proportion of ungradable images was signifcantly greater for nonmydriatic than mydriatic assessments (30% versus 10% ungradable as determined by the NPG). For ETDRS level =35, specifcity ranged from moderate to high (0.70 to 0.96) for the three graders, while sensitivity was poor to moderate (0.38 to 0.71), and the area under the receiver-operating characteristic curves was less than satisfactory (0.67 to 0.71). Conclusions: The low sensitivity of the digital assessments indicates a signifcant proportion of patients in need of referral would not have been referred. These fndings suggest that implementation of a simplifed screening system using nonphotographer clinic staff acquiring nonmydriatic images, with interpretation by an ophthalmologist, should take place with an understanding of potential limitations. © Diabetes Technology Society.