Page 138 - Computational Retinal Image Analysis
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References  131




                     Kugelman et al. [39] use a recurrent neural network to classify layer boundaries,
                  trained on image patches. They segment three layer (NFL, RPE, BM) in Healthy and
                  AMD cases. A CRF postprocessing is applied to create smooth layer boundaries.


                  6  Discussion and conclusion
                  The abundance of publications in OCT layer segmentation of the retina in the last
                  years shows a big interest in furthering this field. With the advent of deep learning
                  big improvements have been achieved in terms of performance, especially in patho-
                  logical cases (AMD, DME, etc.), replacing the state of the art of graph-based meth-
                  ods. The latter cannot deal with highly degenerate retinal layers, where boundaries
                  do not follow mostly horizontal paths or are even completely absent due to atrophy
                  and fluids. Instead, data-driven methods cover a broader spectrum of pathologies and
                  do not need a model-based approach.
                     While there is a large progress in the field, there are still very few of standard pub-
                  lic datasets to be able to compare the results of published methods. This makes it hard
                  to rank algorithms against each other, as they usually test against their own private
                  datasets. In addition, there is disagreement of the assessment on visible anatomy and
                  boundaries thereof in OCT in clinical application. This effect is amplified especially
                  in pathological cases and the lack of reliable metrics, as no single value such as Dice
                  similarity or chamfer distance present a complete picture. A reliable comparison of
                  the performance of published methods becomes thus hard or even impossible. It is
                  therefore of importance to thrive toward extensive, multi-observer and public retinal
                  layer segmentation datasets in OCT.



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