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1. Dynamic Deep Networks for Retinal Vessel Segmentation

   https://doi.org/10.3389/fcomp.2020.00035  

   Khanal, Aashis; Estrada, Rolando (August 2020, Frontiers in Computer Science)
2. Potential measurement error from vessel reflex and multiple light paths in dual‐wavelength retinal oximetry

   https://doi.org/10.1111/aos.15776  

   Beach, James M.; Shoemaker, Benjamin; Eckert, George J.; Harris, Alon; Siesky, Brent; Arciero, Julia C. (October 2023, Acta Ophthalmologica)

   Abstract PurposeThis study aims to characterize the dependence of measured retinal arterial and venous saturation on vessel diameter and central reflex in retinal oximetry, with an ultimate goal of identifying potential causes and suggesting approaches to improve measurement accuracy. MethodsIn 10 subjects, oxygen saturation, vessel diameter and optical density are obtained using Oxymap Analyzer software without diameter correction. Diameter dependence of saturation is characterized using linear regression between measured values of saturation and diameter. Occurrences of negative values of vessel optical densities (ODs) associated with central vessel reflex are acquired from Oxymap Analyzer. A conceptual model is used to calculate the ratio of optical densities (ODRs) according to retinal reflectance properties and single and double‐pass light transmission across fixed path lengths. Model‐predicted values are compared with measured oximetry values at different vessel diameters. ResultsVenous saturation shows an inverse relationship with vessel diameter (D) across subjects, with a mean slope of −0.180 (SE = 0.022) %/μm (20 < D < 180 μm) and a more rapid saturation increase at small vessel diameters reaching to over 80%. Arterial saturation yields smaller positive and negative slopes in individual subjects, with an average of −0.007 (SE = 0.021) %/μm (20 < D < 200 μm) across all subjects. Measurements where vessel brightness exceeds that of the retinal background result in negative values of optical density, causing an artifactual increase in saturation. Optimization of model reflectance values produces a good fit of the conceptual model to measured ODRs. ConclusionMeasurement artefacts in retinal oximetry are caused by strong central vessel reflections, and apparent diameter sensitivity may result from single and double‐pass transmission in vessels. Improvement in correction for vessel diameter is indicated for arteries however further study is necessary for venous corrections. 

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3. Unsupervised vessel trajectory reconstruction

   https://doi.org/10.3389/fams.2023.1124091  

   Chen, Chih-Wei; Huang, Hsin-Hsiung (March 2023, Frontiers in Applied Mathematics and Statistics)

   A trajectory is a sequence of observations in time and space, for examples, the path formed by maritime vessels, orbital debris, or aircraft. It is important to track and reconstruct vessel trajectories using the Automated Identification System (AIS) data in real-world applications for maritime navigation safety. In this project, we use the National Science Foundation (NSF)'s Algorithms for Threat Detection program (ATD) 2019 Challenge AIS data to develop novel trajectory reconstruction method. Given a sequence ofNunlabeled timestamped observations, the goal is to track trajectories by clustering the AIS points with predicted positions using the information from the true trajectoriesΧ. It is a natural way to connect the observed pointx_îwith the closest point that is estimated by using the location, time, speed, and angle information from a set of the points under considerationx_i∀i∈ {1, 2, …,N}. The introduced method is an unsupervised clustering-based method that does not train a supervised model which may incur a significant computational cost, so it leads to a real-time, reliable, and accurate trajectory reconstruction method. Our experimental results show that the proposed method successfully clusters vessel trajectories. 

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4. Drosophila Retinal Patterning

   https://doi.org/10.1038/npg.els.0001511  

   Spencer, Susan A; Johnson, Ruth I; Setu, Bipul (January 2020, Encyclopedia of life sciences)

   The Drosophila eye is an outstanding model system for exploring fundamental mechanisms of growth and development. The adult eye is composed of a perfect hexagonal lattice of ∼750 unit eyes, or ommatidia, each containing precisely 20 well-characterized cells. The eye develops from the eye/antennal imaginal disc, a flattened epithelial sac. During larval and pupal development, cells in the disc grow and undergo compartmentalisation, cell cycle arrest, differentiation, directed movement, and apoptosis, all utilising gene networks and signalling pathways similar to those in vertebrates. The genetic accessibility of Drosophila, together with the precision of eye development, makes the fly retina an extremely useful system with which to investigate the roles of genes and signalling pathways in development. 

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5. Clinical implications of retinal oximetry in retinal vein occlusion: a review

   https://doi.org/10.1111/aos.15066  

   Belamkar, Aditya V.; Jabbehdari, Sayena; Harris, Alon; Hajrasouliha, Amir R. (November 2021, Acta Ophthalmologica)

   Abstract PurposeTo review retinal vein occlusion (RVO) and its relationship with retinal oxygen saturation via automated retinal oximetry in eyes with RVO. MethodsA literature review was performed in PubMed and Medline until October 2021 utilizing specific keywords and cross‐matched reference lists. ResultsThis review found RVO to be associated with risk factors including age, hypertension, cardiovascular and metabolic conditions, male gender, and glaucoma. These may be attributed to a breakdown of regulatory processes in the retina. Retinal venous oxygen saturation (SvO₂) and arteriovenous difference in eyes with central RVO have been found to be reduced and elevated, respectively. The literature indicates variable and contradictory findings in regard to branch RVO and retinal oxygenation. Additionally, ischaemic eyes have been found to have elevated retinal arterial oxygen saturation; however, the literature reports variable results regarding SvO₂levels. Medications have been suggested to increase SvO₂in RVO eyes, which may represent an important mechanism for disease management. Ranibizumab is currently the most studied drug for retinal oxygenation in RVO and has been suggested to increase SvO₂in RVO eyes. In comparison, dexamethasone was found to decrease SvO₂. ConclusionThe current literature on retinal oxygenation in ischaemic subtypes of RVO and in drug therapies is minimal, and further work is required to expand upon our understanding of how ischaemia and drugs influence retinal oxygenation and clinical outcomes. 

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