RETOUCH: The Retinal OCT Fluid Detection and Segmentation Benchmark and Challenge.

Retinal swelling due to the accumulation of fluid is associated with the most vision-threatening retinal diseases. Optical coherence tomography (OCT) is the current standard of care in assessing the presence and quantity of retinal fluid and image-guided treatment management. Deep learning methods have made their impact across medical imaging, and many retinal OCT analysis methods have been proposed. However, it is currently not clear how successful they are in interpreting the retinal fluid on OCT, which is due to the lack of standardized benchmarks. To address this, we organized a challenge RETOUCH in conjunction with MICCAI 2017, with eight teams participating. The challenge consisted of two tasks: fluid detection and fluid segmentation. It featured for the first time: all three retinal fluid types, with annotated images provided by two clinical centers, which were acquired with the three most common OCT device vendors from patients with two different retinal diseases. The analysis revealed that in the detection task, the performance on the automated fluid detection was within the inter-grader variability. However, in the segmentation task, fusing the automated methods produced segmentations that were superior to all individual methods, indicating the need for further improvements in the segmentation performance.

Computing Cyclotorsion in Refractive Cataract Surgery.

GOAL: In refractive surgery, astigmatism-correcting treatments are generally planned with the aid of some diagnostic imaging device and often executed by some computer guided laser system. In the transition from sitting down at a diagnostic device to lying down beneath a laser system, a phenomenon known as cyclotorsion (rotation of the eye within the socket) occurs. Hence, registration between lasers and diagnostic devices is necessary. The purpose of this paper is to present a newly developed algorithm that accomplishes robust registration using images of the patient's iris in the context of laser-assisted cataract surgery, and evaluate its efficacy. METHODS: The proposed iris registration algorithm was tested on real cataract patient images obtained from commercially available devices. Accuracy was measured against manual registrations performed by trained humans. Conservative bounds on success and failure rates were computed using novel statistical methods. RESULTS: The algorithm better approximated the cyclotorsion as averaged over manual measurements from three trained humans than any of the three individual humans, with a 95% tolerance interval of ±1.36(°) . In addition, a success rate ≥ 99.0% was observed for an acceptance threshold setting that allowed for a false registration rate ≤ 1.00*10(-3)%. CONCLUSION: The proposed iris registration algorithm accurately and consistently compensates for cyclotorsion in laser-assisted cataract surgery. SIGNIFICANCE: This paper details the first algorithm to be used for iris registration in laser-assisted cataract surgery. Enabling surgeons to make use of this algorithm in real surgeries is expected to have a significant impact on astigmatism management in cataract surgery.

Cavity mode waves during terahertz radiation from rectangular Bi(2)Sr(2)CaCu(2)O(8 + δ) mesas.

We re-examined the angular dependence of the radiation from the intrinsic Josephson junctions in rectangular mesas of Bi(2)Sr(2)CaCu(2)O(8 + δ), in order to determine if the cavity mode part of the radiation arises from waves across the width w or along the length l of the mesas, associated with 'hot spots' (Wang et al 2010 Phys. Rev. Lett. 105 057002). We derived analytical forms for the angular dependence expected in both cases for a general cavity mode in which the width of the mesa corresponds to an integer multiple of one-half the wavelength of the radiation. Assuming the coherent radiation from the ac Josephson current source and the cavity magnetic surface current density source combine incoherently, fits to the data of Kadowaki et al (2010 J. Phys. Soc. Japan 79 023703) on a mesa with mean l/ω = 5.17 for both wave directions using two models for the incoherent combination were made, which correspond to standing and traveling waves, respectively. The results suggest that the combined output from the uniform ac Josephson current source plus a cavity wave forming along the rectangle length is equally probable as that of the combined output from the uniform ac Josephson current plus a cavity wave across the width. However, for mesas in which nl/2ω is integral, where n is the index of the rectangular TM(z)(n, 0) mode, it is shown that standing cavity mode waves along the length of the mesa do not radiate in the xz plane perpendicular to the length of the mesa, suggesting experiments on such mesas could help to resolve the question.