Development of a multi-field fundus photographing system using a non-mydriatic camera for diabetic retinopathy

Abstract

A new fundus photographing system was developed for diabetic subjects with or without simple diabetic retinopathy using a non-mydriatic fundus camera. Eight internal fixation targets were incorporated in a non-mydriatic fundus camera (TRC-NW5S; TOPCON, Tokyo, Japan), interfaced with a 3CCD color camera. Nine 45° fundus photographs were taken in 22 healthy volunteers and 16 diabetic subjects, and stored as digital images. Fundus images were reconstituted as collages on the monitor and printed out. The combined angle reached 94° in collage, and the average times required for photographing with and without mydriasis were 3 min 26 s and 4 min 36 s, respectively. The concordance of fundus images between the first and second photographs of healthy volunteers with and without mydriasis was 95.4% ( n=22). The quality of the photographs, graded on a five-point scale (5, full) by three doctors, was 4.3±0.6 in the volunteers without mydriasis, 4.7±0.4 in the diabetics without mydriasis, and 4.8±0.3 in the volunteers with mydriasis. In retinas with diabetic retinopathy, the system was able to depict microaneurysms, hemorrhages, hard exudates and soft exudates. This new system was satisfactory for the screening and follow-up of diabetic retinopathy.