Automatic Retinal Nerve Fiber Trajectory Simulation and Quasi-polar Transformation for Detecting Retinal Nerve Fiber Layer Defect in Fundus Images.

The retinal nerve fiber layer defects (RNFLD) provide early objective evidence for many retinal abnormalities, especially early glaucoma. The recent success of deep learning has led to exciting prospects in automating the detection of RNFLD, but it is highly dependent on the availability of large-scale datasets carefully annotated by experienced ophthalmologists, which is both time-consuming and cost-prohibitive. Most previous works on RNFLD detection lack a unified annotation scheme. In addition, they fail to exploit the intrinsic morphological characteristics of retinal nerve fiber bundles (RNFB). This work presents an automatic RNFB tracing method that is applicable not only in automating the RNFLD annotation process, but also in performing a quasi-polar transformation on fundus images for subsequent RNFLD detection tasks. Also, our proposed method paves the way for alleviating the problem of inter-annotator variation incurred merely by different annotation habits among annotators and reducing the noise before the input stage. Experiments reveal that our proposed quasi-polar transformation provides a significant boost to the existing RNFLD detection method and surpasses the state-of-the-art F1 by 4.2%, and that our method also offers a more accurate and reasonable description of RNFLD detection results, which demonstrates the orientation of RNFLD rather than vague position indication.