Search results for " Lenses"

Wavefront holoscopy: application of digital in-line holography for the inspection of engraved marks in progressive addition lenses

2014

Progressive addition lenses (PALs) are engraved with permanent marks at standardized locations in order to guarantee correct centering and alignment throughout the manufacturing and mounting processes. Out of the production line, engraved marks provide useful information about the PAL as well as act as locator marks to re-ink again the removable marks. Even though those marks should be visible by simple visual inspection with the naked eye, engraving marks are often faint and weak, obscured by scratches, and partially occluded and difficult to recognize on tinted or antireflection-coated lenses. Here, we present an extremely simple optical device (named as wavefront holoscope) for visualiza…

Visual and optical performance with hybrid multifocal intraocular lenses

2010

During the past years, the wish to become independent of spectacles has been growing among cataract and presbyopic patients due to many factors, such as the increase in near visual demands, the aesthetic need for a spectacle-free image and ageing of refractive surgery patients, among others. This review assesses recently published studies that analyse visual and optical performance through different metrics of eyes implanted with multifocal intraocular lenses (IOLs), particularly hybrid IOL designs. The published evidence suggests that hybrid multifocal IOLs provide very good outcomes in a number of visual and optical performance parameters. Patients implanted with this type of IOL obtain a…

Acute endothelial failure after cosmetic iris implants (NewIris®)

2011

We report a case of an acute endothelial failure after the implantation of a new cosmetic, colored, artificial iris diaphragm implant called NewIris(®). A 21-year-old woman came to us complaining of progressive loss of vision and pain after NewIris lenses had been implanted. Decreased visual acuity, corneal edema, and increased intraocular pressure in both eyes appeared only 3 weeks after the surgery. The lenses were removed as soon as possible but had already severely affected the endothelial cell count. NewIris implants are an alternative to cosmetic contact lenses, but they are not as safe as other phakic anterior chamber intraocular lenses, nor are they a good option for the patient.

Posterior chamber phakic intraocular lenses after penetrating keratoplasty.

2009

Purpose To evaluate the efficacy, predictability, and safety of a phakic posterior chamber intraocular Collamer lens (ICL) after penetrating keratoplasty (PKP). Setting Fernandez-Vega Ophthalmological Institute, Oviedo, Spain. Methods A myopic or toric ICL was implanted after PKP in eyes unable to wear glasses or contact lenses and for which corneal laser surgery was contraindicated. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive error, and endothelial cell count were recorded preoperatively and 24 months postoperatively. Results Preoperatively, the 15 eyes had myopia from −2.00 to −17.00 diopters (D) or astigmatism from −1.50 to −7.00 D. …

Solvent for removing silicone oil from intraocular lenses: experimental study comparing various biomaterials.

2000

Abstract Purpose To evaluate the effectiveness of a perfluorocarbon—perfluorohexyloctane (PFHO)—in removing silicone oil from different intraocular lenses (IOLs) and determine whether any removal technique enhances the removal of silicone oil. Methods Six IOL materials were analyzed: standard poly(methyl methacrylate) (PMMA), heparin-surface-modified (HSM) PMMA, AcrySof, 2 polyHEMAs with different water contents, and a second-generation SLM-2 silicone. One or 2 μL of a highly viscous silicone oil (5700 cs) was applied to the center of each IOL optic. Perfluorohexyloctane (2 mL) was then used to remove the silicone oil by 1 of 3 techniques: immersion of the IOL in PFHO; irrigation of the sil…

Effect of Decentration on the Optical Quality of Two Intraocular Lenses

2016

To analyze the effect of decentration on the optical quality of two diffractive-refractive intraocular lenses, a bifocal and a trifocal, when displaced laterally (horizontal direction) from the center.The AT LISA 809M IOL (+3.75 D add) with two main foci and the AT LISA tri 839MP intraocular lens with three main foci (Carl Zeiss Meditec AG, Jena, Germany) were analyzed. The optical quality of the intraocular lenses was measured with the PMTF (power and modulation transfer function [MTF] measurement for refractive and diffractive intraocular lenses) optical bench (Lambda-X, Nivelles, Belgium). The optical quality of the lenses was evaluated by the MTF at different object vergences, the avera…

Optical Quality Comparison between Spherical and Aspheric Toric Intraocular Lenses

2014

Purpose To measure and compare the optical quality of spherical and aspheric toric intraocular lenses (IOLs). Methods Wavefront aberrations of AcrySof Toric and IQ Toric IOLs (Alcon Laboratories) for different powers were measured at 3- and 5-mm pupils by Nimo TR0805 instrument. The Zernike coefficients of trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration were evaluated. The point spread functions (PSFs) of each IOL evaluated were calculated from the wavefront aberrations. The PSF images also were calculated from the IOL wavefront aberrations, adding the cornea's aberrations to simulate the optical quality after their implantation. Results Spherical toric IOLs showed…

Incisional Keratotomy to Toric Intraocular Lenses: An Overview of the Correction of Astigmatism in Cataract and Refractive Surgery

2003

Impact of contact lens material and design on the ocular surface.

2018

BACKGROUND: To evaluate the impact on the ocular surface of a daily disposable hydrogel contact lens with high water content compared with two silicone hydrogel daily disposable lenses of lower water content. METHODS: The hydrogel lens assessed was made from nesofilcon A and the silicone hydrogel lenses were made of delefilcon A and stenfilcon A. Contact lens thickness was measured to assess material stability during daily wear, and ocular surface parameters such as tear film osmolarity, tear meniscus area and central corneal thickness were also assessed. Optical quality was analysed for all cases by means of wavefront aberrometry. RESULTS: The nesofilcon A was shown to be the thinnest lens…

Light transmission and ultraviolet protection of contact lenses under artificial illumination

2016

Purpose: To determine the spectral transmission of contact lenses (CLs), with and without an ultraviolet (UV) filter to evaluate their capacity for protection under UV radiation from artificial illumination (incandescent, fluorescent, xenon (Xe) lamps, or white LEDs (light-emitting diode)). Methods: The transmission curves of nine soft CLs were obtained by using a PerkinElmer Lambda 35 UV-vis spectrophotometer. A CIE standard was used for the emission spectra of incandescent and fluorescent lamps, and Xe lamps and white LEDs were measured by using an International Light Technologies ILT-950 spectroradiometer. Results: Five of the nine soft CLs analysed state that they incorporate UV filters…