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https://www.readbyqxmd.com/read/28801659/relationship-between-higher-order-wavefront-aberrations-and-natural-progression-of-myopia-in-schoolchildren
#1
Takahiro Hiraoka, Junko Kotsuka, Tetsuhiko Kakita, Fumiki Okamoto, Tetsuro Oshika
This study investigated the relationship between higher-order aberrations (HOAs) and myopia progression as well as axial elongation in schoolchildren. We examined cycloplegic refraction, axial length, and wavefront aberrations prospectively in 71 myopic children. Changes in cycloplegic refraction and axial length during a 2-year study period were assessed, and their correlations with HOA components were analyzed. Sixty-four subjects ([mean ± SD] 9.2 ± 1.6 years) completed the 2-year examinations. Cycloplegic refraction was significantly changed after 2 years (P < 0...
August 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28801548/virtual-cardiac-monolayers-for-electrical-wave-propagation
#2
Nina Kudryashova, Valeriya Tsvelaya, Konstantin Agladze, Alexander Panfilov
The complex structure of cardiac tissue is considered to be one of the main determinants of an arrhythmogenic substrate. This study is aimed at developing the first mathematical model to describe the formation of cardiac tissue, using a joint in silico-in vitro approach. First, we performed experiments under various conditions to carefully characterise the morphology of cardiac tissue in a culture of neonatal rat ventricular cells. We considered two cell types, namely, cardiomyocytes and fibroblasts. Next, we proposed a mathematical model, based on the Glazier-Graner-Hogeweg model, which is widely used in tissue growth studies...
August 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28791058/stereoacuity-after-wavefront-guided-photorefractive-keratectomy-in-anisometropia
#3
Farid Karimian, Vahid Ownagh, Mohammad Aghazadeh Amiri, Seyed Mehdi Tabatabaee, Nooshin Dadbin
PURPOSE: To determine changes in stereoacuity in anisometropic myopic eyes after photorefractive keratectomy (PRK). METHODS: Myopic patients with at least 1 diopter (D) of anisometropia in sphere, astigmatism, or spherical equivalent who were referred to our hospital for excimer refractive surgery were enrolled as a prospective sequential interventional case series. All patients underwent wavefront-guided photorefractive keratectomy (WFG-PRK) using the Technolas Perfect Vision (217z) Excimer laser machine...
July 2017: Journal of Ophthalmic & Vision Research
https://www.readbyqxmd.com/read/28771544/comparison-of-postoperative-visual-quality-after-smile-and-lasek-for-high-myopia-a-1-year-outcome
#4
Xiaoyu Zhu, Leilei Zou, Manrong Yu, Chen Qiu, Minjie Chen, Jinhui Dai
PURPOSE: To compare the 1-year outcome of visual quality after laser-assisted subepithelial keratomileusis (LASEK) and femtosecond laser-assisted small incision lenticule extraction (SMILE) for high myopia correction. MATERIALS AND METHODS: This prospective, comparative study included 24 eyes of 24 patients in the LASEK group, with a mean spherical equivalent (SE) of -7.59 ± 1.32 diopters, and 26 eyes of 26 patients in the SMILE group, with a mean SE of -7.91 ± 1...
2017: PloS One
https://www.readbyqxmd.com/read/28765756/wavefront-direction-and-cycle-length-affect-left-atrial-electrogram-amplitude
#5
Kazuki Iso, Ichiro Watanabe, Rikitake Kogawa, Yasuo Okumura, Koichi Nagashima, Keiko Takahashi, Ryuta Watanabe, Masaru Arai, Kimie Ohkubo, Toshiko Nakai, Atsushi Hirayama, Mizuki Nikaido
BACKGROUND: The relationship between atrial electrogram (EGM) characteristics in atrial fibrillation (AF) and those in sinus rhythm (SR) are generally unknown. The activation rate and direction may affect EGM characteristics. We examined characteristics of left atrial (LA) EGMs obtained during pacing from different sites. METHODS: The study included 10 patients undergoing pulmonary vein isolation for AF. Atrial EGMs were recorded from a 64-pole basket catheter placed in the LA, and bipolar EGM amplitudes from the distal electrode pair (1-2) and proximal electrode pair (6-7) from 8 splines were averaged...
August 2017: Journal of Arrhythmia
https://www.readbyqxmd.com/read/28755010/switchable-phase-and-polarization-singular-beams-generation-using-dielectric-metasurfaces
#6
Yanliang He, Ying Li, Junmin Liu, Xiaoke Zhang, Yao Cai, Yu Chen, Shuqing Chen, Dianyuan Fan
Singular beams which possess helical phase wavefront or spatially inhomogeneous polarization provide new freedom for optical field manipulation. However, conventional schemes to produce the singular beams have difficulty in realizing the flexible switch between different singular beams. In this work, we have experimentally demonstrated the capability of dielectric metasurfaces to generate three types of singular beams and switch between them at working wavelength of 1550  nm. We have shown vortex beam and cylindrical vector beam generation with single metasurface and cylindrical vector vortex beam generation with two cascaded metasurfaces...
July 28, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28751782/reconstruction-of-local-frequencies-for-recovering-the-unwrapped-phase-in-optical-interferometry
#7
Julio C Estrada, Jose L Marroquin, Orlando M Medina
In optics, when interferograms or digital holograms are recorded and their phase is recovered, it is common to obtain a wrapped phase with some errors, noise and artifacts such as singularities due to the non linearities of the demodulation process. This paper shows how to reconstruct the frequency field of the wrapped phase by using adaptive Gabor filters. Gabor filters are Gaussian quadrature filters tuned in at a certain frequency. We adapt these Gabor filters by tuning them locally and estimating the frequency using wrapped finite differences of the estimated phase...
July 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28746183/visual-outcomes-after-balanced-salt-solution-infiltration-during-lenticule-separation-in-small-incision-lenticule-extraction-for-myopic-astigmatism
#8
RANDOMIZED CONTROLLED TRIAL
Ting Liu, Xiaomin Zhu, Kaijian Chen, Ji Bai
To evaluate the refractive outcomes of balanced salt solution infiltration during small-incision lenticule extraction (SMILE).This randomized prospective study enrolled 52 patients (104 eyes) with myopic astigmatism. Patients underwent SMILE to correct the myopic astigmatism in Daping Hospital of the Third Military Medical University between January and July 2013. One eye of each patient received traditional SMILE (control group) and the other received a modified SMILE procedure (liquid infiltration group)...
July 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28742033/the-impact-of-model-based-clutter-suppression-on-cluttered-aberrated-wavefronts
#9
Kazuyuki Dei, Brett Byram
Recent studies reveal that both phase aberration and reverberation play a major role in degrading ultrasound image quality. We previously developed an algorithm for suppressing clutter, but we have not yet tested it in the context of aberrated wavefronts. In this study, we evaluate our previously reported algorithm, called aperture domain model image reconstruction (ADMIRE), in the presence of phase aberration and in the presence of multipath scattering and phase aberration. We use simulations to investigate phase aberration corruption and correction in the presence of reverberation...
July 20, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28736670/wavefront-sensorless-adaptive-optics-oct-with-the-done-algorithm-for-in-vivo-human-retinal-imaging-invited
#10
Hans R G W Verstraete, Morgan Heisler, Myeong Jin Ju, Daniel Wahl, Laurens Bliek, Jeroen Kalkman, Stefano Bonora, Yifan Jian, Michel Verhaegen, Marinko V Sarunic
In this report, which is an international collaboration of OCT, adaptive optics, and control research, we demonstrate the Data-based Online Nonlinear Extremum-seeker (DONE) algorithm to guide the image based optimization for wavefront sensorless adaptive optics (WFSL-AO) OCT for in vivo human retinal imaging. The ocular aberrations were corrected using a multi-actuator adaptive lens after linearization of the hysteresis in the piezoelectric actuators. The DONE algorithm succeeded in drastically improving image quality and the OCT signal intensity, up to a factor seven, while achieving a computational time of 1 ms per iteration, making it applicable for many high speed applications...
April 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28736657/high-temporal-resolution-aberrometry-in-a-50-eye-population-and-implications-for-adaptive-optics-error-budget
#11
Jessica Jarosz, Pedro Mecê, Jean-Marc Conan, Cyril Petit, Michel Paques, Serge Meimon
We formed a database gathering the wavefront aberrations of 50 healthy eyes measured with an original custom-built Shack-Hartmann aberrometer at a temporal frequency of 236 Hz, with 22 lenslets across a 7-mm diameter pupil, for a duration of 20 s. With this database, we draw statistics on the spatial and temporal behavior of the dynamic aberrations of the eye. Dynamic aberrations were studied on a 5-mm diameter pupil and on a 3.4 s sequence between blinks. We noted that, on average, temporal wavefront variance exhibits a n(-2) power-law with radial order n and temporal spectra follow a f(-1...
April 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28732617/vector-analysis-of-astigmatic-changes-after-small-incision-lenticule-extraction-and%C3%A2-wavefront-guided-laser-in-situ-keratomileusis
#12
Mounir A Khalifa, Ahmed M Ghoneim, Mohamed Shafik Shaheen, David P Piñero
PURPOSE: To evaluate and compare the efficacy of the astigmatic correction after wavefront-guided laser in situ keratomileusis (LASIK) and small-incision lenticule extraction (SMILE) and in myopic eyes. DESIGN: Prospective case series. SETTING: Horus Vision Correction Center and Ellite Vision Correction Center, Alexandria, Egypt. METHODS: Myopic eyes with astigmatism up to 4.00 diopters (D) had wavefront-guided LASIK or small-incision lenticule extraction...
June 2017: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/28726938/design-and-characterization-of-a-plasmonic-doppler-grating-for-azimuthal-angle-resolved-surface-plasmon-resonances
#13
Kel-Meng See, Fan-Cheng Lin, Jer-Shing Huang
We present a two-dimensional plasmonic Doppler grating (PDG) for broadband and azimuthal angle-resolved nanophotonic applications. The PDG consists of a set of non-concentric circular rings mimicking the wavefronts of a moving point source that exhibits the Doppler effect and thereby offers a continuous azimuthal angle-dependent lattice momentum for photon-plasmon coupling. The center and span of the working frequency window are fully designable for optimal performance in specific applications. We detail the design, fabrication and optical characterization of the PDG...
August 3, 2017: Nanoscale
https://www.readbyqxmd.com/read/28717573/in-vivo-digital-wavefront-sensing-using-swept-source-oct
#14
Abhishek Kumar, Lara M Wurster, Matthias Salas, Laurin Ginner, Wolfgang Drexler, Rainer A Leitgeb
Sub-aperture based digital adaptive optics is demonstrated in a fiber based point scanning optical coherence tomography system using a 1060 nm swept source laser. To detect optical aberrations in-vivo, a small lateral field of view of ~[Formula: see text] is scanned on the sample at a high volume rate of 17 Hz (~1.3 kHz B-scan rate) to avoid any significant lateral and axial motion of the sample, and is used as a "guide star" for the sub-aperture based DAO. The proof of principle is demonstrated using a micro-beads phantom sample, wherein a significant root mean square wavefront error (RMS WFE) of 1...
July 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28713849/glare-suppression-by-coherence-gated-negation
#15
Edward Haojiang Zhou, Atsushi Shibukawa, Joshua Brake, Haowen Ruan, Changhuei Yang
Imaging of a weak target hidden behind a scattering medium can be significantly confounded by glare. We report a method, termed coherence gated negation (CGN), that uses destructive optical interference to suppress glare and allow improved imaging of a weak target. As a demonstration, we show that by permuting through a set range of amplitude and phase values for a reference beam interfering with the optical field from the glare and target reflection, we can suppress glare by an order of magnitude, even when the optical wavefront is highly disordered...
October 2016: Optica
https://www.readbyqxmd.com/read/28708166/low-photon-count-based-digital-holography-for-quadratic-phase-cryptography
#16
Inbarasan Muniraj, Changliang Guo, Ra'ed Malallah, James P Ryle, John J Healy, Byung-Geun Lee, John T Sheridan
Recently, the vulnerability of the linear canonical transform-based double random phase encryption system to attack has been demonstrated. To alleviate this, we present for the first time, to the best of our knowledge, a method for securing a two-dimensional scene using a quadratic phase encoding system operating in the photon-counted imaging (PCI) regime. Position-phase-shifting digital holography is applied to record the photon-limited encrypted complex samples. The reconstruction of the complex wavefront involves four sparse (undersampled) dataset intensity measurements (interferograms) at two different positions...
July 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28708155/adaptive-aberration-correction-of-a-5%C3%A2-%C3%A2-j-6-6%C3%A2-%C3%A2-ns-200%C3%A2-%C3%A2-hz-solid-state-nd-yag-laser
#17
Xin Yu, Lizhi Dong, Boheng Lai, Ping Yang, Shanqiu Chen, Wenjin Liu, Shuai Wang, Guomao Tang, Jisi Qiu, Zhijun Kang, Yueliang Liu, Hao Liu, Yong Liu, Zhongwei Fan, Bing Xu
In this Letter, we present an adaptive aberration correction system to simultaneously compensate for aberrations and reshaping the beams. A low-order aberration corrector is adapted. In this corrector, four lenses are mounted on a motorized rail, whose positions can be obtained using a ray tracing method based on the beam parameters detected by a wavefront sensor. After automatic correction, the PV value of the wavefront is reduced from 26.47 to 1.91 μm, and the beam quality β is improved from 18.42 to 2...
July 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28701800/design-transform-and-control-of-optical-field-in-discrete-optical-system-an-example
#18
Hongchang Deng, Yonggui Yuan, Libo Yuan
A discrete optical system can broaden the spatial distribution of the input light through optical coupling in array waveguides, just like diffraction in continuous media. Here, we theoretically demonstrate several kinds of control methods of optical field propagation in a discrete optical system, which is composed of an Airy fiber with two perpendicular arrayed cores. A brief transform mechanism between Gaussian and Airy beam propagation in such a fiber is presented. The wavefront of the output beam from the Airy fiber is actually dependent on the phased arrayed modulation of coupling array cores...
July 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28695661/relationships-between-gastric-slow-wave-frequency-velocity-and-extracellular-amplitude-studied-by-a-joint-experimental-theoretical-approach
#19
T H-H Wang, P Du, T R Angeli, N Paskaranandavadivel, J C Erickson, T L Abell, L K Cheng, G O'Grady
BACKGROUND: Gastric slow wave dysrhythmias are accompanied by deviations in frequency, velocity, and extracellular amplitude, but the inherent association between these parameters in normal activity still requires clarification. This study quantified these associations using a joint experimental-theoretical approach. METHODS: Gastric pacing was conducted in pigs with simultaneous high-resolution slow wave mapping (32-256 electrodes; 4-7.6 mm spacing). Relationships between period, velocity, and amplitude were quantified and correlated for each wavefront...
July 11, 2017: Neurogastroenterology and Motility: the Official Journal of the European Gastrointestinal Motility Society
https://www.readbyqxmd.com/read/28681436/human-eyes-do-not-need-monochromatic-aberrations-for-dynamic-accommodation
#20
Paula Bernal-Molina, Iván Marín-Franch, Antonio J Del Águila-Carrasco, Jose J Esteve-Taboada, Norberto López-Gil, Philip B Kruger, Robert Montés-Micó
PURPOSE: To determine if human accommodation uses the eye's own monochromatic aberrations to track dynamic accommodative stimuli. METHODS: Wavefront aberrations were measured while subjects monocularly viewed a monochromatic Maltese cross moving sinusoidally around 2D of accommodative demand with 1D amplitude at 0.2 Hz. The amplitude and phase (delay) of the accommodation response were compared to the actual vergence of the stimulus to obtain gain and temporal phase, calculated from wavefront aberrations recorded over time during experimental trials...
July 5, 2017: Ophthalmic & Physiological Optics: the Journal of the British College of Ophthalmic Opticians (Optometrists)
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