Search results for " Lens"
showing 10 items of 510 documents
Objective and subjective evaluation of photic phenomena after monofocal and multifocal intraocular lens implantation11The authors have no commercial …
1999
Abstract Objective To objectively measure and compare halo, flicker, and glare disability in pseudophakic eyes with monofocal (MONO) and multifocal (MULTI) intraocular lenses (IOLs) with respect to the influence of corneal surface quality, astigmatism, and age. Design Prospective case series. Participants This clinical trial involved 28 eyes of 28 patients after small-incision cataract surgery with a MONO silicone IOL and 28 eyes of 28 patients with zonal-progressive silicone IOL. Intervention A computer program objectively determined halo, glare, and flicker. Corneal surface quality and astigmatism were measured using computerized videokeratography. Ray-tracing analysis was performed based…
In vitro optical performance of a new aberration-free intraocular lens
2014
To assess the optical performance of the new EnVista intraocular lens (IOL). Four aspheric IOLs were evaluated; the new EnVista is one amoung them. This IOL, similarly to the Z-Flex HB and the Bi-Flex 1.8 667AB ones, has a neutral aspheric design, whereas the fourth IOL under test (AcrySof IQ IOL SN60WF) presents a negative spherical aberration (SA). The IOL’s aberration patterns were measured in vitro, by setting them up on an optical bench. From these aberration-pattern data, the modulation transfer function (MTF), the average modulation values, and the points spread function (PSF) were calculated. Furthermore, in order to assess the potential optical quality that these IOLs would yield o…
Optical quality comparison between 2 collagen copolymer posterior chamber phakic intraocular lens designs
2014
Purpose To compare the optical quality in vitro of 2 designs of the Visian Implantable Collamer Lens phakic intraocular lens (pIOL) for different powers and optical apertures. Setting University of Valencia, Valencia, Spain. Design Experimental study. Methods The Nimo TR1504 deflectometry device was used to measure the V4c pIOL, which has a smaller optic diameter, and the V5 pIOL, which has a larger optic diameter. The pIOLs were measured for −3.00 diopters (D), −6.00 D, −9.50 D, and −10.50 D at different optical apertures from 3.00 to 6.00 mm depending on the IOL power and model. The root mean square of higher-order aberrations (RMS HOAs) was analyzed. The Strehl ratio, point-spread functi…
In vitro optical performance of nonrotational symmetric and refractive-diffractive aspheric multifocal intraocular lenses: impact of tilt and decentr…
2012
Purpose To evaluate the optical quality of Acrysof Restor SN6AD1 refractive–diffractive +3.00 D and Lentis Mplus LS-312 nonrotational symmetric +3.00 D aspheric multifocal intraocular lenses (IOLs) and analyze the effect of tilt and decentration. Setting University of Valencia, Valencia, and University of Murcia, Murcia, Spain. Design Experimental study. Methods An artificial model eye was used to measure wavefront aberrations of both IOL models. The modulation transfer function (MTF) and point-spread function (PSF) were calculated for a 5.0 mm pupil and under 5 situations: centered, 0.2 mm and 0.4 mm decentered, and 2 degrees and 4 degrees tilted. Results The refractive–diffractive IOL had…
Physical compensation of phase curvature in digital holographic microscopy by use of programmable liquid lens.
2015
Quantitative phase measurements obtained with digital holographic microscopes are strongly dependent on the optical arrangement of the imaging system. The nontelecentric operation provides phase measurements affected by a parabolic phase factor and requires numerical postprocessing, which does not always remove all the perturbation. Accurate phase measurements are achieved by using the imaging system in telecentric mode. Unfortunately, this condition is not accomplished when a commercial microscope is used as the imaging system. In this paper, we present an approach for obtaining accurate phase measurements in nontelecentric imaging systems without the need for numerical postprocessing. The…
Tolerance to rotation of toric monofocal and bifocal intraocular lenses. A theoretical study
2018
Abstract This manuscript aims to evaluate the tolerance to rotation of a toric monofocal and a toric bifocal intraocular lenses with different cylinder powers. Theoretical designs based on wavefront aberrations were created to simulate a toric monofocal and a toric bifocal intraocular lens. Cylinder power ranged from −1 D to −6 D, in steps of −1 D. Tolerance to rotation was estimated by the visual Strehl ratio based on the optical transfer function (VSOTF) metric. Tolerance to rotation for both monofocal and bifocal intraocular lenses decreased when the cylinder power increased. For the bifocal design studied, the tolerance to rotation was larger for the near focus than for the far, however…
Standardization of sperm motility analysis by using CASA-Mot for Atlantic salmon (Salmo salar), European eel (Anguilla anguilla) and Siberian sturgeo…
2019
[EN] It is essential to define an optimized standard method to assess the fish sperm quality to minimize the differences between the results obtained by different laboratories. Only this optimization and standardization can make them useful from academia to industry. This study presents the validation of sperm motility assessment using a CASA-Mot system for three endangered diadromous fish species: European eel (Anguilla anguilla), Atlantic salmon (Salmo salar) and Siberian sturgeon (Acipenser baerii). To attain this goal, different technical and data processing methods were tested: 1) magnification lens (×10 and ×20), 2) Spermtrack® reusable chambers (10 and 20¿¿m depth) and 3) different f…
Ortokeratoloģijas lēcas dizaina ietekme uz acs aksiālā garuma izmaiņām.
2020
Maģistra darbs ir uzrakstīts angļu valodā uz 59 lapaspusēm. Tas satur 24 attēlus, 3 tabulas un 85 literatūras atsauces. Pētījuma mērķis bija novērtēt miopijas kontroles ortokeratoloģijas lēcu formas un optiskās zonas platuma ietekmi uz miopijas progresijas mazināšanu. Darbā tika analizēti 12 bērnu ar augstu miopijas pakāpi ortokeratoloģijas rezultāti, iegūti kopā no 19 acīm. Tika salīdzinātas acs aksiālā garuma izmaiņas, bērniem nēsājot parastas ortokeratoloģijas lēcas un lietojot specializētās miopijas kontroles ortokeratoloģijas lēcas. Rezultāti parādīja, ka specializētās ortokerotoloģijas lēcas daudz efektīvāk samazina acs aksiālā garuma palielināšanos nekā parastās lēcas. Atslēgas vārdi…
Kontaktlēcu pielietojums redzes asuma uzlabošanai pacientiem ar anizometropijas ambliopiju
2017
Bakalaura darbs ir uzrakstīts angļu valodā uz 25 lapaspusēm. Tas satur 9 attēlus, 1 tabulu, 21 atsauci uz literatūras avotiem. Darba uzdevums ir novērtēt, vai kontaktlēcu lietošana pozitīvi ietekmē redzes funkcijas anizometropijas ambliopijas gadījumā. Pētījumā piedalījās 16 pacienti (24 – 54 g.v.). Pēc pilnas refrakcijas korekcijas izrakstīšanas katru mēnesi 6 mēnešu laikā tika novērtēts lēcas novietojums, iespējamās lēcas ģeometrijas, redzes asuma un binokularitātes izmaiņas. Visiem pacientiem uzlabojās redzes asums (0,4 ± 0,2, decimālās vienībās), novēroja pirmās pakāpes binokularitātes pazīmes un 11 pacientiem varēja noteikt rupju stereoredzi. Iegūtie rezultāti demonstrē, ka kontaktlēcu…
Effect of the color of the intraocular lens on optical and visual quality
2014
Purpose: To analyze the optical quality of intraocular lenses (IOL) with an orange (PC440Y) and a yellow (SN60AT) filter, and correlate these results with the visual quality of patients with these implants. Setting: Fisabio Oftalmología Médica, Valencia, Spain. Design: Randomized prospective study. Materials and Methods: The IOL optical quality was determined using the modulation transfer function (MTF) and the spectral transmission. The visual quality of 87 eyes with cataract (51 with orange filter and 36 with yellow filter) was determined by best corrected visual acuity (BCVA) and contrast sensitivity function (CSF) under photopic and mesopic conditions. To analyze the results, we use a S…