Replication study: Development and validation of deep learning algorithm for detection of diabetic retinopathy in retinal fundus photographs
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We have replicated some experiments in 'Development and validation of a deep learning algorithm for detection of diabetic retinopathy in retinal fundus photographs' that was published in JAMA 2016; 316(22). We re-implemented the methods since the source code is not available. The original study used fundus images from EyePACS and three hospitals in India for training their detection algorithm. We used a different EyePACS data set that was made available in a Kaggle competition. For evaluating the algorithm's performance the benchmark data set Messidor-2 was used. We used the similar Messidor-Original data set to evaluate our algorithm's performance. In the original study licensed ophthalmologists re-graded all their obtained images for diabetic retinopathy, macular edema, and image gradability. Our challenge was to re-implement the methods with publicly available data sets and one diabetic retinopathy grade per image, find the hyper-parameter settings for training and validation that were not described in the original study, and make an assessment on the impact of training with ungradable images. We were not able to reproduce the performance as reported in the original study. We believe our model did not learn to recognize lesions in fundus images, since we only had a singular grade for diabetic retinopathy per image, instead of multiple grades per images. Furthermore, the original study missed details regarding hyper-parameter settings for training and validation. The original study may also have used image quality grades as input for training the network. We believe that deep learning algorithms should be easily replicated, and that ideally source code should be published so that other researchers can confirm the results of the experiments. Our source code and instructions for running the replication are available at: https://github.com/mikevoets/jama16-retina-replication.
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