Optical coherence tomography (OCT) is a recently established imaging technique to describe different information about the internal structures of an object and to image various aspects of biological tissues. OCT image segmentation is mostly introduced on retinal OCT to localize the intra-retinal boundaries. Here, we review some of the important image segmentation methods for processing retinal OCT images. We may classify the OCT segmentation approaches into five distinct groups according to the image domain subjected to the segmentation algorithm. Current researches in OCT segmentation are mostly based on improving the accuracy and precision, and on reducing the required processing time. There is no doubt that current 3-D imaging modalities are now moving the research projects toward volume segmentation along with 3-D rendering and visualization. It is also important to develop robust methods capable of dealing with pathologic cases in OCT imaging.
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Arq Bras Oftalmol
January 2025
Ophthalmology Department, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey.
Sci Adv
January 2025
CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China.
Contextuality is a hallmark feature of the quantum theory that captures its incompatibility with any noncontextual hidden-variable model. The Greenberger-Horne-Zeilinger (GHZ)-type paradoxes are proofs of contextuality that reveal this incompatibility with deterministic logical arguments. However, the GHZ-type paradox whose events can be included in the fewest contexts and that brings the strongest nonclassicality remains elusive.
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January 2025
State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China.
Hong-Ou-Mandel (HOM) interference is the foundation of quantum optics to test the degree of indistinguishability of two incoming photons, playing a key role in quantum communication, sensing, and photonic quantum computing. Realizing high-visibility HOM interference with massively parallel optical channels is challenging due to the lack of available natural optical references for aligning independent arrayed laser pairs. Here, we demonstrate 50 parallel comb-teeth pairs of continuous-wave weak coherent photons HOM interference using two independently frequency post-aligned soliton microcombs (SMCs), achieving an average fringe visibility over 46%.
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January 2025
School of Materials Science and Engineering, Peking University, Beijing 100871, P.R. China.
Microcavity exciton polaritons (polaritons) as part-light part-matter quasiparticles garner considerable attention for Bose-Einstein condensation at elevated temperatures. Recently, halide perovskites have emerged as promising room-temperature polaritonic platforms because of their large exciton binding energies and superior optical properties. However, currently, inducing room-temperature nonequilibrium polariton condensation in perovskite microcavities requires optical pulsed excitations with high excitation densities.
View Article and Find Full Text PDFJ Neuroophthalmol
January 2025
Department of Ophthalmology (JGJ-C, TE, Y-HC, LRD, RAG), Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; Frank H. Netter Medical School (JGJ-C), North Haven, Connecticut; and Department of Anesthesiology (DZ), Critical Care and Pain Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts.
Background: Patients with craniosynostosis are at high risk of developing elevated intracranial pressure (ICP) causing papilledema and secondary optic atrophy. Diagnosing and monitoring optic neuropathy is challenging because of multiple causes of vision loss including exposure keratopathy, amblyopia, and cognitive delays that limit examination. Peripapillary hyperreflective ovoid mass-like structures (PHOMS) are an optical coherence tomography (OCT) finding reported in association with papilledema and optic neuropathy.
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