Choroidal Haller's and Sattler's Layer Thickness Measurement Using 3-Dimensional 1060-nm Optical Coherence Tomography

Objectives: To examine the feasibility of automatically segmented choroidal vessels in three-dimensional (3D) 1060-nmOCT by testing repeatability in healthy and AMD eyes and by mapping Haller's and Sattler's layer thickness in healthy eyes Methods: Fifty-five eyes (from 45 healthy subjects and 10 with non-neovascular age-related macular degeneration (AMD) subjects) were imaged by 3D-1060-nmOCT over a 36°x36° field of view. Haller's and Sattler's layer were automatically segmented, mapped and averaged across the Early Treatment Diabetic Retinopathy Study grid. For ten AMD eyes and ten healthy eyes, imaging was repeated within the same session and on another day. Outcomes were the repeatability agreement of Haller's and Sattler's layer thicknesses in healthy and AMD eyes, the validation with ICGA and the statistical analysis of the effect of age and axial eye length (AL) on both healthy choroidalsublayers. Results: The coefficients of repeatability for Sattler's and Haller's layers were 35% and 21% in healthy eyes and 44% and 31% in AMD eyes, respectively. The mean±SD healthy central submacular field thickness for Sattler's and Haller's was 87±56 µm and 141±50 µm, respectively, with a significant relationship for AL (P<.001). Conclusions: Automated Sattler's and Haller's thickness segmentation generates rapid 3D measurements with a repeatability correspondingto reported manual segmentation. Sublayers in healthy eyes thinnedsignificantly with increasing AL. In the presence of the thinned Sattler's layer in AMD, careful measurement interpretation is needed. Automatic choroidal vascular layer mapping may help to explain if pathological choroidal thinning affects medium and large choroidal vasculature in addition to choriocapillaris loss.Macular Vision Research FoundationMedical University of ViennaEuropean Union (project FUN OCT (FP7 HEALTH, contract no. 201880))European Union (FAMOS (FP7 ICT 317744))European Union (FWF-NFN ‘Photoacoustic imaging in biology and Medicine’, Oesterreichische Nationalbank Jubilaumsfonds projekt (14294))National Institutes of Health (U.S.) (NIH R01-EY011289-27)Deutsche Forschungsgemeinschaft (DFG-GSC80-SAOT)Deutsche Forschungsgemeinschaft (DFG-GSC80-SAOT, DFG-HO-1791/11-1)Carl Zeiss Meditec, Inc.FEMTOLASERS (Firm)Christian Doppler Societ

Increasing the Performance of the Canadian Hydrological Model using Lookup Tables

The climate of cold regions is fragile and could be easily threatened by human activities. Hydrological processes play an important role in the climate of cold regions, and using computational models to simulate cold-region hydrological processes helps people understand past hydrological events and predict future ones. With the need to get more accurate simulation results, more complex computational models are often required. However, the complexity of models is often limited by available computational resources. Therefore, improving the computational efficiency of model simulations is an urgent task for hydrological researchers and software developers. The Canadian Hydrological Model (CHM) is a modular software package that is used to simulate cold-region hydrological processes. CHM uses an efficient surface discretization, unstructured triangular meshes, to reduce the number of discretization elements, which in turn decreases the complexity of cold-region hydrological models. CHM also employs parallelization to make models more efficient. By profiling the performance of CHM, we find that there are some computationally intensive functions inside CHM that are evaluated repeatedly. Lookup tables (LUTs) followed by optional interpolation or Taylor series approximation are common optimizations to replace such direct function evaluations. These optimizations can decrease the complexity of cold-region hydrological models further. The Function Comparator (FunC) is a C++ library that can automatically create one-dimensional LUTs for continuous univariate functions on uniformly spaced grids. In this thesis, we use FunC to implement LUTs for two computationally intensive and repeatedly called functions in CHM, achieving an improvement of around 20% in the performance of CHM in the sense of running time on two cold-region hydrological simulations. In the first step, we identify two computationally intensive and repeatedly called functions by profiling the performance of CHM, determine the error tolerances and the ranges of inputs for their LUT implementations, and use FunC to implement linear interpolation LUTs for both functions in CHM. In the second step, we run CHM with and without LUT implementations on a coldregion hydrological simulation with a small domain. We verify that CHM with LUT implementations produces correct output and show that there is around an 18% improvement in the performance of CHM. In the third step, we run the same CHM with and without LUT implementations on a cold-region hydrological simulation with a large domain. We again verify that CHM with LUT implementations produces correct output and show that there is around a 21% improvement in the performance of CHM

Repeatability of Sattler's and Haller's layer thickness mapping and ETDRS measurements in non-neovascular AMD.

<p>Sattler's layer and Haller's layer are color mapped. Imaging was performed twice at the same session (left and middle column) and on a different day (right column). The vessel segmentation and indocyanine green angiography images of this eye are depicted in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099690#pone-0099690-g003" target="_blank">Figure 3</a>.</p