Search results for " Lenses"
showing 10 items of 190 documents
Ahromatopsijas izpausmju korekcija ar krāsainām kontaktlēcām
2017
MĒRĶIS: Novērtēt filtru kontaktlēcu (KL) pielietojumu ahromatopsijas simptomu korekcijai. METODE: Pētījumā piedalījās 8 dalībnieki (6 sievietes un 2 vīrieši) vecumā no 8 mēnešiem līdz 25 gadiem, periodā no 2012. līdz 2016.gadam. Pēc oftalmoloģiskās pārbaudes un ahromatopsijas noteikšanas, tika veikta speciālās krāsainās KL pielaikošanas procedūra. Pacientu atbildes tika noteiktas ar anketas palīdzību un noteikts apžilbšanas laiks ar un bez piedāvātām KL. SECINĀJUMI: filtru KL samazināja fotofobiju; apžilbšanas laiks kļuvis salīdzināms ar normālā redzes gadījumu; dalībnieki atzinīgi novērtē psiholoģiskos un sociālos ieguvumus ar izrakstītām filtru KL.
Physicochemical Surface Properties of Various Intraocular Lenses
2001
<i>Purpose:</i> It is of major interest to understand how intraocular lens (IOL) surfaces interact with aqueous humor or tissues after implantation. Important parameters to describe the physicochemical surface properties are the contact angle and critical surface tension. Therefore, we performed measurements of the contact angle and critical surface tension of several commercially available IOLs. <i>Setting:</i> Department of Ophthalmology, Johannes Gutenberg University, Mainz, University Eye Hospital, Tübingen, and Max Planck Institute for Polymer Research, Mainz, Germany. <i>Methods:</i> A total of 17 commercially available standard quality IOL types (6…
Schematic eye models to mimic the behavior of the accommodating human eye
2018
A simplified version of the human eye is known as schematic eye model. Since the first attempts in the middle of the 19th century, numerous approaches describing new schematic eye models have been introduced. Some of them are able to describe the accommodation ability of the human eye. Accommodative schematic eyes could be of great interest since they are able to explain the functionality of the human eye and they can be easily used for different research purposes. Some of these include the design and testing of multifocal ophthalmic solutions, evaluation of the effect of optical aberrations on the retinal image quality, and study of the optical performance of the eye at different distances…
Validation of a spectral light scattering method to differentiate large from small particles in intraocular lenses
2017
A psychophysical approach has been designed to measure straylight from intraocular lenses (IOLs) in vitro. This approach uses a clinical straylight meter (C-Quant) and an observer's eye as optical detector. Based on this, we introduced a method for study of straylight-wavelength dependency for IOLs. This dependency can be used to distinguish between 2 types of scattering particles (small and large) as defined by Mie theory. Validation was performed using a turbidity standard and scattering filters. Several IOLs were analyzed to identify potential scattering sources. Large particles were found to predominate in scattering from the studied lenses. This was confirmed by straylight-angular depe…
Modulation transfer function in refractive-diffractive multifocal intraocular lenses in vitro
2007
Purpose: The optical quality of two types of multifocal, hybrid refractive-diffractive, intraocular lenses (IOL) is analyzed in vitro. Following the EN-ISO international standard, the IOLs’ modulation transfer functions (MTF) are determined for both distance and near vision. The behaviour of these curves when the pupil size varies is studied. Methods: The IOLs analyzed were: AcrySoft ResTor SN60D3 (Alcon) and Tecnis ZM900 (AMO). The MTF was calculated from the cross line-spread function recorded with the OPAL Vector System (Image Science Ltd. Oxford) by using fast Fourier transform techniques. The artificial eye model used simulates in vivo conditions of the anterior chamber including an ar…
Estimation of the mechanical properties of the eye through the study of its vibrational modes.
2017
Measuring the eye's mechanical properties in vivo and with minimally invasive techniques can be the key for individualized solutions to a number of eye pathologies. The development of such techniques largely relies on a computational modelling of the eyeball and, it optimally requires the synergic interplay between experimentation and numerical simulation. In Astrophysics and Geophysics the remote measurement of structural properties of the systems of their realm is performed on the basis of (helio-)seismic techniques. As a biomechanical system, the eyeball possesses normal vibrational modes encompassing rich information about its structure and mechanical properties. However, the integral a…
Kontaktlēcu ietekme uz redzes asumu pacientiem ar neregulāru radzeni
2017
Darbs uzrakstīts angļu valodā uz 39 lapām. Tas satur 11 attēlus, 1 aptaujas lapu, 11 tabulas and 24 atsauces uz literatūras avotiem. Mērķis: darba galvenais mērķis ir salīdzināt parastās gāzu caurlaidīgās kontaktlēcas ar gāzu caurlaidīgajām intralimbālajām lēcām. Metodes: gāzu caurlaidīgās intralimbālās lēcas tika novērtētas, pētījuma dalībniekiem aizpildot anketu. Rezultāti: pētījuma dalībnieki deva priekšroku gāzu caurlaidīgajām intralimbālajām lēcām un novērtēja to sniegto komfortu, tomēr nebija būtiskas atšķirības starp iegūto redzes asumu abu lēcu gadījumā. Secinājumi: izvērtējot katra pacienta individuālo sutāciju, optometrists var apsvērt intralimbālo lēcu izrakstīšanu pecientam, lai…
Kontaktlēcu pacientu līdzestība un nelīdzestības iemesli Latvijā
2019
Bakalaura darbs ir uzrakstīts latviešu valodā uz 73 lapām. Darbs sastāv no ievada, teorētiskās un praktiskās daļas. Darbs satur 42 attēlus, 6 tabulas, 3 pielikumus un 63 literatūras avotu atsauces. Bakalaura darba mērķis: Novērtēt kontaktlēcu pacientu līdzestības un nelīdzestības iemeslus Latvijā. Bakalaura darba uzdevumi: 1. Ar anketēšanas palīdzību noskaidrot un salīdzināt kontaktlēcu lietotāju un optometristu asistentu zināšanas par kontaktlēcu lietošanu un kopšanu. 2. Noskaidrot kontaktlēcu lietotāju biežākās sūdzības. 3. Novērtēt kontaktlēcu lietotāju līdzestību. Metode: Izveidotas 3 anketas. Kontaktlēcu lietotāju anketa izveidotā divās valodas (latviešu un krievu valodā) un sastāv no …
Generation of programmable 3D optical vortex structures through devil’s vortex-lens arrays
2013
Different spatial distributions of optical vortices have been generated and characterized by implementing arrays of devil's vortex lenses in a reconfigurable spatial light modulator. A simple design procedure assigns the preferred position and topological charge value to each vortex in the structure, tuning the desired angular momentum. Distributions with charges and momenta of the opposite sign have been experimentally demonstrated. The angular velocity exhibited by the phase distribution around the focal plane has been visualized, showing an excellent agreement with the simulations. The practical limits of the method, with interest for applications involving particle transfer and manipula…
Tear Film Surface Quality in Modern Daily Disposable Contact Lens Wear
2021
Objectives As reported previously, tear film surface quality (TFSQ) should be considered in contact lens (CL) fitting. This study followed noninvasive keratograph tear film break-up time (NIKBUT) in CL wearers for 12 months to validate its clinical utility in predicting CL performance. Methods Fifty-five subjects (M/F=17/38) aged 26±4 years were prescribed silicone hydrogel or hydrogel CLs. The study included baseline measurements without CLs; 2 visits for CL fitting and control; follow-up after 3, 6, and 12 months of CL wear; and postwear visit without CLs. Ocular Surface Disease Index (OSDI), 8-Item Contact Lens Dry Eye Questionnaire (CLDEQ-8), first and mean NIKBUT (F/M-NIKBUT), fluoresc…