Search results for "Refractive"
showing 9 items of 559 documents
Fluctuaciones refractivas en la diabetes mellitus. Implicaciones en la praxis optométrica
2014
El objetivo de este trabajo se centra en cómo los niveles de glucosa en sangre en personas que padecen de diabetes mellitus, afecta a la fluctuación refractiva del ojo, y cuáles pueden ser las implicaciones en la praxis optométrica. Para lograr este objetivo, se ha llevado a cabo una investigación de tipo documental basada en la revisión y el análisis de la literatura científica general y específica existente sobre la temática. Se ha analizado cómo la glucemia afecta a las diferentes partes del ojo de una forma independiente, a corto y a largo plazo. El trabajo se ha estructurado en varios apartados donde se abordan las siguientes temáticas: relevancia de la enfermedad en el mundo, resumen …
Calidad de visión y satisfacción del paciente usuario de pantallas de visualización de datos tras cirugía refractiva
2007
Objetivo: Evaluar la influencia en la calidad de vida y satisfacción de los trabajadores usuarios de pantallas de visualización de datos (PVD) que se asocia a la mejora de la función visual tras queratomileusis in situ con láser excimer (LASIK). Métodos: Estudio observacional y longitudinal en una población de 96 pacientes intervenidos de cirugía refractiva con láser excimer según técnica LASIK mediante aplicación de un cuestionario construído al efecto aplicado antes y después de cirugía por un observador independiente. Resultados: Agudeza visual y refracción ocular han mejorado tras LASIK, siendo el índice de eficacia de 1.1. La sensibilidad al contraste tras cirugía mejora en todas las f…
Active lighting applied to three-dimensional reconstruction of specular metallic surfaces by polarization imaging
2006
International audience; In the field of industrial vision, the three-dimensional inspection of highly reflective metallic objects is still a delicate task. We deal with a new automated three-dimensional inspection system based on polarization analysis. We first present an extension of the shape-from-polarization method for dielectric surfaces to metallic surfaces. Then, we describe what we believe to be a new way of solving the ambiguity concerning the normal orientation with an active lighting system. Finally, applications to shape-defect detection are discussed, and the efficiency of the system to discriminate defects on specular metallic objects made by stamping and polishing is presente…
Measurement of Low Concentration of Nanosized Objects Suspended in a Liquid Medium
2018
The new optical scheme of refractometer with temperature stabilisation 10-2 °C is developed, which allows measuring a refractive index of the sample with accuracy not worse than 10-5; dependence of refraction index on concentration of SiO2 nanoparticles in liquid suspension is obtained within the framework of the research.
Optical quality of hyperopic and myopic phakic intraocular lenses
2013
Aims: To assess and compare the optical quality of the myopic and hyperopic implantable collamer lens (ICL) from its wavefront aberrations for different powers and pupil diameters. Settings and Design: Prospective study. Material and Methods: The wavefront aberrations of two myopic (−3 and −6 diopters (D)) and two hyperopic V4b ICLs (+3 and +6D) were measured in vitro . To assess and compare the optical quality of different powers of ICLs, we analyzed the root mean square (RMS) of total higher order aberrations (HOAs), trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration at 3- and 4.5-mm pupil. In addition, the point spread functions (PSFs) of each ICL evaluated were ca…
Ray optics behavior of flux avalanche propagation in superconducting films
2015
Experimental evidence of wave properties of dendritic flux avalanches in superconducting films is reported. Using magneto-optical imaging the propagation of dendrites across boundaries between a bare NbN film and areas coated by a Cu layer was visualized, and it was found that the propagation is refracted in full quantitative agreement with Snell's law. For the studied film of 170 nm thickness and a $0.9\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{m}$ thick metal layer, the refractive index was close to $n=1.4$. The origin of the refraction is believed to be caused by the dendrites propagating as an electromagnetic shock wave, similar to damped modes considered previously for normal …
Associations of Children’s Close Reading Distance and Time Spent Indoors with Myopia, Based on Parental Questionnaire
2022
Purpose: To study the association of parents’ reports about their children’s near work and outdoor habits with myopia in their children. Methods: Data from a questionnaire study conducted in 1983 among Finnish schoolchildren were reanalyzed. Vision screening had been performed for all the schoolchildren (n = 4961) in the 1st, 5th, and 8th grades (7-, 11-, and 15-year-olds) in an area of Central Finland. The questionnaire, including information about myopia, was returned by 4305 (86.7%) participants. Items concerned parents’ estimates of their child’s habitual reading distance, time spent indoors as compared with age peers, daily near work, outdoors time, and parents&…
Krustotās un nekrustotās stereoredzes izmaiņas pēc LASIK operācijas
2021
Maģistra darbs uzrakstīts angļu valodā uz 37 lappusēm. Tas satur 10 attēlus, 9 tabulas un darbam ir 49 atsauces uz literatūras avotiem. Pētījuma mērķis bija novērtēt krustotās un nekrustotās disparitātes stereoredzes asumu pirms redzes refraktīvās operācijas, divus, četrus un sešus mēnešus pēc operācijas. Pētījumā piedalījās 102 acu klīnikas pacienti – 65 sievietes un 37 vīrieši vecumā no 19 līdz 45 gadiem. Visiem bija miopija vai miopija ar astigmatismu. Jaunais izveidotais izkliedēto punktu globālais stereoredzes datorizētais tests dod iespēju novērtēt abus disparitātes veidus. Rezultātu analīzē tika secināts, ka nav novērojamas statistiski būtiskas izmaiņas stereoredzes asumā pirms un pē…
Virskorekcijas pielietojamība tuvredzības progresijas novērtēšanā ortokeratoloģijas pacientiem
2022
Darbs ir uzrakstīts angļu valodā uz 93 lapaspusēm. Tas satur 49 attēlus, 24 tabulas un 95 atsauces uz literatūras avotiem. Šī darba mērķis ir pārbaudīt, vai virskorekcija ir derīga metode tuvredzības progresēšanas novērtēšanai ortokeratoloģijā. Hipotēze ir atrast lielākas izmaiņas gados jaunākiem pacientiem nekā pieaugušajiem, kā tas ir norādīts literatūrā. Pētījumā iekļauti 192 Eiropeīdās rases subjekti vecumā no 6 līdz 56 gadiem (vidēji 19,61±10,30). Izmantojot retrospektīvu analīzi, no objektīva BOZR kontaktlēcas parametra tiek iegūta virskorekcija (ORX). Jaunākiem cilvēkiem ir lielākas ORX vērtības, bet pieaugušajiem nav atšķirības (p<0,05). Vidēji tuvredzība progresēja par –0,18±0,44 D…