Automated Detection and Differentiation of Drusen, Exudates, and Cotton-Wool Spots in Digital Color Fundus Photographs for Diabetic Retinopathy Diagnosis

Abstract

To describe and evaluate a machine learning based, automated system to detect exudates and cotton-wool spots in digital color fundus photographs, and differentiate them from drusen, for early diagnosis of diabetic retinopathy. Three hundred retinal images from one eye of three hundred patients with diabetes were selected from a diabetic retinopathy telediagnosis database (non-mydriatic camera two field photography); 100 with previously diagnosed ‘bright’ lesions, and 200 without. A machine learning computer program was developed that can identify and differentiate among drusen, (hard) exudates, and cotton-wool spots. A human expert standard for the 300 images was obtained by consensus annotation by two retinal specialists. Sensitivities and specificities of the annotations on the 300 images by the automated system and a third retinal specialist were determined. The system achieved an area under the ROC curve of 0.95 and sensitivity/specificity pairs of 0.95/0.88 for the detection of ‘bright’ lesions of any type, and 0.95/0.86, 0.70/0.93 and 0.77/0.88 for the detection of exudates, cotton-wool spots and drusen, respectively. The third retinal specialist achieved pairs of 0.95/0.74 for ‘bright’ lesions, and 0.90/0.98, 0.87/0.98 and 0.92/0.79 per lesion type. An machine learning based, automated system capable of detecting exudates and cotton-wool spots and differentiating them from drusen in color images obtained in community based diabetic patients has been developed and approaches the performance level of that of retinal experts. If the machine learning can be improved with additional training datasets, it may be useful to detect clinically important ‘bright’ lesions, enhance early diagnosis and reduce suffering from visual loss in patients with diabetes.