Search results for "contact lens"
showing 10 items of 119 documents
Visual Comparison of an Artificial Pupil Contact Lens to Monovision
2012
PURPOSE To assess and compare the effects of contact-lens based artificial pupil design and monovision correction on visual performance. METHODS In a cross-over study design, 22 presbyopic patients (age range 50 to 64 years) were evaluated using artificial pupil contact lens on the non-dominant eye and monovision. After 1 month, binocular distance visual acuity (BDVA), binocular near visual acuity (BNVA), defocus curve, binocular distance contrast sensitivity, binocular near contrast sensitivity, and stereoacuity were measured, under photopic conditions (85 cd/m2), in each patient after contact lens fitting. Moreover, BDVA and binocular distance contrast sensitivity were examined under meso…
Axial Elongation following Cataract Surgery during the First Year of Life in the Infant Aphakia Treatment Study
2012
PURPOSE To compare ocular axial elongation in infants after unilateral cataract surgery corrected with a contact lens (CL) or primary intraocular lens (IOL) implantation. METHODS Baseline axial length (AL) was measured at the time of cataract surgery (1-6 months) and at age 1 year. AL at baseline and age 1 year and the change in length/mo were analyzed in relation to treatment modality, cataractous versus fellow eye, and age at surgery using linear mixed models. RESULTS Mean baseline AL did not differ between the CL and IOL groups for either cataractous or fellow eyes. Eyes with cataracts were shorter than fellow eyes by an average of 0.6 mm (95% confidence interval [CI], 0.4-0.8 mm; P < 0.…
Visual Performance of a Multifocal Toric Soft Contact Lens
2012
PURPOSE To evaluate the visual performance of the Proclear multifocal toric contact lens (CL; CooperVision, US) for both presbyopia and astigmatism correction. METHODS In this crossover study design, 20 presbyopic subjects with astigmatism were fitted in a random order with either Proclear multifocal toric CL or Proclear toric single vision distance CL (DCL) combined with reading spectacles. After 1 month, high-contrast distance visual acuity, near high-contrast visual acuity, distance contrast sensitivity (CS) under photopic and mesopic conditions without and with glare, near CS, defocus curve, and stereopsis were measured. Subjects were then refitted with the alternative correction, and t…
Effect of Multizone Refractive Multifocal Contact Lenses on Standard Automated Perimetry
2012
PURPOSE The aim of this study was to evaluate whether the creation of 2 foci (distance and near) provided by multizone refractive multifocal contact lenses (CLs) for presbyopia correction affects the measurements on Humphreys 24-2 Swedish interactive threshold algorithm (SITA) standard automated perimetry (SAP). METHODS In this crossover study, 30 subjects were fitted in random order with either a multifocal CL or a monofocal CL. After 1 month, a Humphrey 24-2 SITA standard strategy was performed. The visual field global indices (the mean deviation [MD] and pattern standard deviation [PSD]), reliability indices, test duration, and number of depressed points deviating at P<5%, P<2%, P<1%, an…
Comparison of the influence of corneo-scleral and scleral lenses on ocular surface and tear film metrics in a presbyopic population
2018
PURPOSE: To assess and compare the effect of the corneo-scleral lenses (C-ScL) and scleral lenses (ScL) on tear film parameters and central corneal thickness (CCT) in healthy presbyopic subjects. METHODS: Thirty subjects wore two contact lenses (CLs), randomly assigned, of neutral power, but of different diameters, 12.7mm (C-ScL) and 18mm (ScL) and being equal in the others parameters: material (HS100) and centre thickness (0.29mm). At baseline, 20min after insertion and at 8h, the tear meniscus area (TMA) and CCT was measured (with optical coherence tomography) as well as tear osmolarity. RESULTS: TMA revealed statistical differences for both lenses at 20min (p<0.001), and also at 8h (p=0.…
Effect of sport-tinted contact lenses for contrast enhancement on retinal straylight measurements
2008
PURPOSE: To investigate the effect of two tinted contact lenses (CL) designed for outdoor sports activity on the psychometric determination of retinal straylight using the compensation comparison method. METHODS: Thirteen emmetropic subjects were randomly fitted with two different tinted Nike Maxsight (Bausch & Lomb, Rochester, NY, USA) CL in one eye, while the contralateral eye was fitted with a clear lens made of the same material (Optima 38, Bausch & Lomb). Three valid straylight measurements were taken on each eye before and a few minutes after lens insertion, when lens stabilization had occurred. RESULTS: The subjects' mean straylight values were 0.90 +/- 0.09 at baseline and 0.95 +/- …
In vitro power profiles of daily disposable contact lenses
2012
Abstract Purpose To evaluate and compare the distribution of refractive power within the optic zone of different soft contact lenses and to investigate the effect of lens decentration on the power profiles. Methods The Nimo TR1504 instrument was used to measure the optical power across different aperture diameters (from 1.5 mm to 5.5 mm in steps of 0.5 mm) of four daily disposable contact lenses: DAILIES TOTAL1, Proclear 1-Day, SofLens daily disposable and 1-DAY ACUVUE MOIST. Measurements were performed using a wet cell. Power data were evaluated when contact lenses were in its centered position and after inducing different amounts of lens decentration (from 0.2 mm to 1.0 mm in steps of 0.2…
True and Apparent Oxygen Permeabilities of Contact Lenses
1992
We studied the passage of oxygen through some commercially available contact lenses. Oxygen diffusion coefficients were determined by the time-lag method and a 201T Redher permeometer was used to measure the oxygen permeability and transmissibility by the polarographic method. The measurements were carried out at room temperature with 0.09% sodium chloride physiologic solution. The following types of lenses were tested: (1) 12 lenses of cellulose acetate butyrate (CAB) of a mean thickness of 0.194 mm (observed Dk approximately 6.3 barrers) (1 barrier is equivalent to 10(-11) cm3 of O2 (STP).cm2/cm3.s.mm Hg). (2) 13 lenses of a cross-linked polyhydroxyethyl methacrylate (2-HEMA), manufacture…
Biological oxygen apparent transmissibility of hydrogel contact lenses with and without organosilicon moieties.
2003
The instrument oxygen transmissibility (IOT) of organosilicon hydrogels, measured by electrochemical procedures, is 5-10 times larger than that of conventional hydrogels. A method is described that allows the estimation of the oxygen tension at the lens-cornea interface for closed- and open-eyelids situations by combining the IOT of the hydrogels and corneal parameters such as corneal thickness, corneal permeability and oxygen flux across the cornea. From these results the biological oxygen apparent transmissibility (BOAT) is obtained, an important parameter which an multiplication with the pressure of oxygen on the external part of the lens gives the oxygen flux onto the cornea. Contact le…
Optical power distribution of refractive and aspheric multifocal contact lenses: Effect of pupil size
2015
Abstract Purpose To evaluate the power profile within the optic zone of different designs of multifocal contact lenses (CLs) and to analyze how the effect of pupil size could impact on their optical performance. Methods The optical power distribution within the optic zones of multifocal CLs was measured by the Nimo TR1504 (LAMBDA-X, Belgium). The multifocal CLs under study were the Acuvue Bifocal, the Acuvue Oasys for Presbyopia, the PureVision Multifocal and the PureVision 2 for Presbyopia. Each design was considered in all their available addition powers. All lenses had a nominal power of −3.0D. At the same time, three lenses of each model were considered and five consecutive readings of …