A COMPUTERIZED SYSTEM FOR LOCALIZATION OF DIABETIC LESIONS FROM FUNDUS IMAGES

A computerized system for the localization of diabetic lesions from fu ndus photographs is described. The coordinates for each lesion in rela tion to reference points are determined from fundus images projected o n a digitizing table. The program accepts some variation in coordinate s for a single lesion, still to be recorded as the same lesion in a se ries of photographs, and the magnitude of this variation is adjustable . The data obtained from the localization program are transferred to a register program yielding the following parameters: number of lesions , new lesions, lost lesions, variable lesions, time of presence for lo st lesions. These data can be further exported into Microsoft Excel 4, for analysis of large patient materials. An intra-observer error of 0 % and an inter-observer error of 1.1% was found in localization of les ions from fundus images. The program was insensitive to small variatio ns in the fundus pictures, but comparisons of 30-degrees and 60-degree s photographs of the same fundus, or 20-degrees deviation of gaze, ind uced identification errors in 2.9% and 11.9% of localizations, respect ively. With this system new parameters on diabetic fundus images can b e obtained. The significance of these parameters in the progression of diabetic retinopathy will be analyzed in further studies.