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Seungwoo Shin, Doyeon Kim, Kyoohyun Kim, YongKeun Park
We present a multimodal approach for measuring the three-dimensional (3D) refractive index (RI) and fluorescence distributions of live cells by combining optical diffraction tomography (ODT) and 3D structured illumination microscopy (SIM). A digital micromirror device is utilized to generate structured illumination patterns for both ODT and SIM, which enables fast and stable measurements. To verify its feasibility and applicability, the proposed method is used to measure the 3D RI distribution and 3D fluorescence image of various samples, including a cluster of fluorescent beads, and the time-lapse 3D RI dynamics of fluorescent beads inside a HeLa cell, from which the trajectory of the beads in the HeLa cell is analyzed using spatiotemporal correlations...
June 15, 2018: Scientific Reports
Geon Kim, Moosung Lee, SeongYeon Youn, EuiTae Lee, Daeheon Kwon, Jonghun Shin, SangYun Lee, Youn Sil Lee, YongKeun Park
Unlike mammalian erythrocytes, amphibian erythrocytes have distinct morphological features including large cell sizes and the presence of nuclei. The sizes of the cytoplasm and nuclei of erythrocytes vary significantly over different species, their environments, or pathophysiology, which makes hematological studies important for investigating amphibian species. Here, we present a label-free three-dimensional optical quantification of individual amphibian erythrocytes from frogs Pelophylax nigromaculatus (Rana nigromaculata)...
June 15, 2018: Scientific Reports
Shizuka Koh, Cynthia I Tung, Yasushi Inoue, Vishal Jhanji
The precorneal tear film is maintained by blinking and exhibits different phases in the tear cycle. The tear film serves as the most anterior surface of the eye and plays an important role as a first refractive component of the eye. Alterations in tear film dynamics may cause both vision-related and ocular surface-related symptoms. Although the optical quality associated with the tear film dynamics previously received little attention, objective measurements of optical quality using wavefront sensors have enabled us to quantify optical aberrations induced by the tear film...
June 15, 2018: British Journal of Ophthalmology
Kerr Brogan, Charles J M Diaper, Alan P Rotchford
BACKGROUND/AIMS: To report refractive outcomes from an National Health Service (NHS) cataract surgery service and assess if results meet suggested benchmark standard. METHODS: Details of all patients undergoing cataract surgery in the Southern General and New Victoria hospitals in Glasgow, UK, between November 2006 and December 2016 were prospectively entered into an electronic database. Patients were reviewed 4 weeks postoperatively in the eye clinic and underwent refraction at their local optometrist prior to this appointment...
June 15, 2018: British Journal of Ophthalmology
D Turnbull, P Franke, J Katz, J P Palastro, I A Begishev, R Boni, J Bromage, A L Milder, J L Shaw, D H Froula
Flying focus is a technique that uses a chirped laser beam focused by a highly chromatic lens to produce an extended focal region within which the peak laser intensity can propagate at any velocity. When that intensity is high enough to ionize a background gas, an ionization wave will track the intensity isosurface corresponding to the ionization threshold. We report on the demonstration of such ionization waves of arbitrary velocity. Subluminal and superluminal ionization fronts were produced that propagated both forward and backward relative to the ionizing laser...
June 1, 2018: Physical Review Letters
Matthias P L Sentis, Fabrice R A Onofri, Fabrice Lamadie
The image of the photonic jet (also called caustic) formed by a large, transparent, and spherical particle, reconstructed by digital in-line holography, is shown to be similar to the Airy pattern observed at the focus of a diffraction-limited lens. The analysis of this image, real or virtual depending on whether the particle relative refractive index is above or below one, allows characterizing the particle composition via its refractive index. Experiments clearly demonstrate the value of this method for the simultaneous 3D characterization and differentiation of the dynamics, size, and composition of gas, liquid, and solid particles in multiphase flows...
June 15, 2018: Optics Letters
X Roselló-Mechó, M Delgado-Pinar, J L Cruz, A Díez, M V Andrés
UV-assisted fabrication of gratings using photosensitive fibers is a well-established technique, based on the UV-induced permanent modification of the refractive index of the fiber material. As a result, the absorption coefficient is also changed. Here, we exploit the thermal sensitivity of whispering gallery mode resonances of the fiber itself to measure the profile of the heating along an irradiated fiber versus the input power and for different UV radiation intensities. Our technique allows discriminating between the absorption and scattering contributions to the overall losses, by comparing the results obtained with our technique with direct transmission measurements...
June 15, 2018: Optics Letters
Yu Zhang, Xiaoyun Tang, Yaxun Zhang, Wenjie Su, Zhihai Liu, Xinghua Yang, Jianzhong Zhang, Jun Yang, Kyunghwan Oh, Libo Yuan
We proposed and experimentally demonstrated 3-dimensional dark traps for low refractive index bio-cells using a single optical fiber Bessel beam. The Bessel beam was produced by concatenating single-mode fiber and a step index multimode fiber, which was then focused by a high refractive index glass microsphere integrated on the fiber end facet. The focused Bessel beam provided two dark fields along the axial direction, where stable trapping of low refractive index bio-cells was realized in a high refractive index liquid bath...
June 15, 2018: Optics Letters
Daphne Maurer, Suzanne P McKEE
Amblyopia is a developmental disorder that affects the spatial vision of one or both eyes in the absence of an obvious organic cause; it is associated with a history of abnormal visual experience during childhood. Subtypes have been defined based on the purported etiology, namely, strabismus (misaligned eyes) and/or anisometropia (unequal refractive error). Here we consider the usefulness of these subclassifications.
January 2018: Visual Neuroscience
Hui Qiao, Jiamin Wu, Xiaoxu Li, Morteza H Shoreh, Jingtao Fan, Qionghai Dai
Tomographic phase microscopy (TPM) is a unique imaging modality to measure the three-dimensional refractive index distribution of transparent and semitransparent samples. However, the requirement of the dense sampling in a large range of incident angles restricts its temporal resolution and prevents its application in dynamic scenes. Here, we propose a graphics processing unit-based implementation of a deep convolutional neural network to improve the performance of phase tomography, especially with much fewer incident angles...
June 2018: Journal of Biomedical Optics
Tao Guo, Peng Gao, Li Fang, Li Guo, Yuchen Fan, Changgen Liu
The present prospective clinical observational study aimed to evaluate the efficacy of Toric intraocular lenses (IOL) to achieve rotational stability and astigmatism correction in eyes with high myopia. A total of 27 consecutive cataract patients (39 eyes) with pre-existing corneal astigmatism (1.5-3.5 D) were divided into two groups according to their refractive status: One group of 18 eyes with high myopia -(12.5-6.0 D) and another group consisting of 21 eyes with emmetropia or low myopia (-3.0-0.0 D). All eyes underwent cataract phacoemulsification surgeries by the same surgeon, with the implantation of an AcrySof® Toric IOL at the pre-designed degree...
June 2018: Experimental and Therapeutic Medicine
Jun Cao, Fenghua Qi, Senlin Yan, Lifa Zhang
There is growing interest in designing waveguide couplers with low reflections. Using impedance-tunable transformation optics, we propose a coordinate transformation technique in the design of compact three-dimensional waveguide couplers. To transmit electromagnetic waves between two coaxial waveguides with different inner and outer radii in the microwave range, a suitable impedance function is derived to reduce the impedance mismatch at the boundary, which make the fabrication process being simplified due to the reduced set of transformation media(dielectric response materials only)...
June 14, 2018: Scientific Reports
Andreea Campu, Frederic Lerouge, Denis Chateau, Frederic Chaput, Patrice Baldeck, Stephane Parola, Dana Maniu, Ana-Maria Craciun, Adriana Vulpoi, Simion Astilean, Monica Focsan
In this work, we demonstrate the feasibility of gold bipyramidal-shaped nanoparticles (AuBPs) to be used as active plasmonic nanoplatforms for the detection of the biotin-streptavidin interaction in aqueous solution via both Localized Surface Plasmon Resonance and Surface Enhanced Raman Scattering (LSPR/SERS). Our proof of concept exploits the precise attachment of the recognition element at the tips of AuBPs where the electromagnetic field is stronger, which is beneficial to the surface sensitivity of longitudinal LSPR on the local refractive index, and to the electromagnetic enhancement of SERS activity too...
June 15, 2018: Analytical Chemistry
Sarat A Badmus, Ayotunde I Ajaiyeoba, Bernice O Adegbehingbe, Oluwatoyin H Onakpoya, Adenike O Adeoye, Sanyaolu A Ameye
PURPOSE: The study aimed at determining the relationship between refraction and anthropometric measurements and the relationship between the level of education and refractive status in a Nigerian young adult population. MATERIALS AND METHODS: Healthy volunteers from the students and staff of a teaching hospital in South-Western Nigeria were studied. Demographic profiles including participants' highest educational status, parental educational level, and the age at first formal school enrollment were documented...
January 2018: Middle East African Journal of Ophthalmology
Alison Bruce, Gillian Santorelli, John Wright, John Bradbury, Brendan T Barrett, Marina Bloj, Trevor A Sheldon
PURPOSE: To determine presenting visual acuity levels and explore the factors associated with failing vision screening in a multi-ethnic population of UK children aged 4-5 years. METHODS: Visual acuity (VA) using the logMAR Crowded Test was measured in 16,541 children in a population-based vision screening programme. Referral for cycloplegic examination was based on national recommendations (>0.20logMAR in one or both eyes). Presenting visual impairment (PVI) was defined as VA >0...
June 13, 2018: Eye
C O Sayaka Kato, Kimiya Shimizu, Kazutaka Kamiya, Hitoshi Ishikawa, Akihito Igarashi
This study aimed to assess changes in pupil size, uncorrected visual acuity, refraction, and the direct and consensual light reflexes after instillation of brimonidine 0.1% in healthy subjects. The investigation comprised 46 eyes of 23 healthy subjects with no eye diseases in whom brimonidine 0.1% was instilled in the right eye. Pupil size was measured quantitatively under photopic and scotopic conditions, uncorrected visual acuity, refraction, and direct and consensual light reflexes before and at 1, 6, and 24 h after instillation...
June 13, 2018: Scientific Reports
Huamao Miao, Xun Chen, Mi Tian, Yingjun Chen, Xiaoying Wang, Xingtao Zhou
BACKGROUND: To investigate refractive outcomes and optical quality after implantation of posterior chamber phakic implantable collamer lens with a central hole (ICL V4c) to correct high myopia. METHODS: Sixty seven eyes of 38 patients who underwent ICL V4c implantation were enrolled. The mean preoperative spherical equivalent (SE) was - 12.44 ± 3.15 D (range: - 6.63 to - 20.50 D). The refractive outcomes and optical quality of the eyes at postoperative 1 and 3 months were evaluated and compared...
June 14, 2018: BMC Ophthalmology
Kyle Gorkowski, Neil M Donahue, Ryan C Sullivan
We present a new algorithm for the analysis of whispering gallery modes (WGMs) found in the cavity enhanced Raman spectra retrieved from optically tweezed droplets. Our algorithm improves the computational scaling when analyzing core-shell droplets (i.e. phase-separated or biphasic droplets) in the aerosol optical tweezers (AOT), making it computationally practical to analyze spectra collected at a few Hz over hours-long experiments. This enables the determination of the size and refractive index of both the core and shell phases with high accuracy, at 0...
June 13, 2018: Environmental Science. Processes & Impacts
Mohammed S Alhazmi, Craig W Butler, Barbara M Junghans
BACKGROUND: The use of patient simulators in ophthalmic education appears limited. This study examines the effects of the addition of the 'Virtual Refractor' patient simulator learning activity into a short unit preparing students to determine the power of the spectacle lenses required by patients in a clinic. METHODS: Twenty-four year one optometry students were randomly assigned to either the simulator-intervention group (n = 12) or the non-intervention group...
June 12, 2018: Clinical & Experimental Optometry: Journal of the Australian Optometrical Association
Petteri Parkkila, Mohamed Elderdfi, Alex Bunker, Tapani Viitala
Supported lipid bilayers (SLBs) have been used extensively as an effective model of biological membranes, in the context of in vitro biophysics research, and the membranes of liposomes, in the context of the development of nanoscale drug delivery devices. Despite numerous surface-sensitive techniques having been applied to their study, the comprehensive optical characterization of SLBs using surface plasmon resonance (SPR) has not been conducted. In this study, Fresnel multilayer analysis is utilized to effectively calculate layer parameters (thickness and refractive indices) with the aid of dual-wavelength and dispersion coefficient analysis, in which the linear change in refractive index as a function of wavelength is assumed...
June 12, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
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