Diabetic retinopathy screening with nonmydriatic fundus camera(1 and 3 fields) vs ETDRS standard

Abstract

Abstract Purpose: To evaluate the ability to determine single lesions and to grade clinical levels of diabetic retinopathy (DR)using nonmydriatic(NM)digital color retinal images compared to Early Treatment Diabetic Retinopathy Study(ETDRS)7 standard 35‐mm stereoscopic color fundus photos. Methods: 80 eyes of 42 diabetic patients with wide spectrum of DR lesions were enrolled.Nonsimultaneous 45°‐field non stereoscopic digital color images were taken from 1 central field(1F) and from 3 fields (3F) with a NM automatic fundus camera(Nidek Technologies, Italy).After dilatation standard 30° ETDRS photos were obtained with Topcon TRC50IA(Japan).The images obtained were analysed by 2 independent, masked readers evaluating lesion‐by‐lesion to assess the ETDRS grading and the clinical severity of the disease according the International proposed 5‐stage disease severity classification. Results: Comparison of single lesions among 1F or 3F images and ETDRS fields revealed good agreement for hard exudates(k= 0.74 and k=0.75 respectively);moderate agreement for hemorrhages and/or microaneurysms(k=0.49, k= 0.60),cotton wool spots(k=0.41, K=0.49)and retinal new vessels(k=0.40, k=0.43).The agreement was fair for clinically significant macular edema(k=0.40, k=0.39).There was substantial agreement between 3F and ETDRS images for moderate non‐proliferative and proliferative DR(k=0.70 and k= 0.89 respectively),while it was moderate between 1F and ETDRS images. Conclusions: The automatic non‐mydriatic 3 field system may be an effective tool to determine the level of DR and to identify the need for prompt referral to the ophthalmologist, even when applied as a telemedicine tool. It is still controversial if one 45° image is adequate for DR screening.