Photoscreening for diabetic retinopathy: a comparison of image quality between film photography and digital imaging

Purpose: Retinal images from patients attending an urban screening centre before and after the transition from film photography to digital image acquisition were analysed for quality of image. Methods: A total of 1946 diabetic patients, aged 12−92 years (mean 55.6 ± 14.88 years), were included in this retrospective study of retinal screening techniques. Each imaging group was subdivided into age‐matched groups. In all subjects pupils were pharmacologically dilated before photography. The images were reviewed by the same three experienced observers and graded at the time of screening from grade 1 (excellent quality) to grade 4 (unreadable). Results: Of 938 patients in the film group, 31.3% had excellent images, 38.2% good, 22.7% poor and 7.8% were unreadable. Of the 1008 patients in the digital imaging group, 25.3% had excellent images, 46.3% good, 14.6% poor and 13.8% were unreadable. A significant difference was observed in patients over 65 years of age who exhibited a threefold increase in failure rate with digital imaging (33.7% v 11.3%)(P