A COMPARISON OF DIGITAL RETINAL IMAGES AND 35 MM COLOR TRANSPARENCIESIN DETECTING AND GRADING DIABETIC-RETINOPATHY

We compared digital retinal images and 35 mm colour transparencies tak en with the Canon CR5 retinal camera for the detection and grading of diabetic retinopathy in a clinical setting, in a randomized, blinded s tudy of diabetic patients with a spectrum of severity of diabetic reti nopathy. Forty patients were photographed, giving a total of 75 eyes i ncluding non-diabetic eyes as controls. Images were graded according t o the validated European guidelines. There was exact agreement between grades obtained from both the 2 field 45 degrees 35 mm colour transpa rencies and digital images in 93.3 % (70/75) of eyes, with Cohen's Kap pa statistic for the comparison being 0.92. Overall, when grading from the digital images 5.3 % (4/75) eyes were undergraded with three case s of sight threatening diabetic retinopathy (STDR) graded as non-sight threatening (NSTDR) (3/48, 6.3 %). One eye was overgraded (1/75, 1.3 %). Two of the three cases of STDR undergraded as NSTDR had small numb ers of intra-retinal microvascular abnormalities (IRMA) discernible on the colour transparencies but which were not visible from the digital image. The third had multiple small cotton wool spots graded as laser photocoagulation scars from the digital images. In conclusion there i s good to excellent agreement between retinopathy grades using the Can on CR5 digital retinal imaging system compared to 35 mm colour transpa rencies. (C) 1998 by John Wiley & Sons, Ltd.