Search results for "visual acuity"
showing 10 items of 456 documents
Optical and Visual Simulation of Standard and Modified Spherical Aberration Implantable Collamer Lens Post Myopic LASIK Surgery
2013
To evaluate the visual quality achieved in patients undergoing standard or modified implantable Collamer lens (ICL) to correct residual myopic error after laser-assisted in situ keratomileusis (LASIK) surgery.The adaptive optics visual simulator was used to simulate LASIK surgery of moderate and high myopia with a myopic regression corrected by a standard and modified ICL. Visual acuity (VA) and contrast sensitivity (CS) were measured in 14 subjects at 3- and 4.5-mm pupil. Point spread function and simulated retinal images were calculated.Comparing LASIK plus standard ICL and LASIK plus modified ICL simulations, for moderate myopia, VA improvement was less than 1 line in all VA contrasts an…
Image quality and visual performance in the peripheral visual field following photorefractive keratectomy.
2002
ABSTRACT PURPOSE: A theoretical and experimental study was performed to assess the possible effects of photorefractive keratectomy (PRK) on retinal image quality and thresholds in the peripheral visual field. METHODS: Simple optical calculations suggest that although the quality of the retinal image at the fovea of the postoperative PRK eye may be comparable to that in an emmetropic eye, images in the peripheral field may be markedly worse, since peripheral ray bundles may pass partly through ablated and partly through unablated cornea, giving a simultaneous-vision bifocal effect. This would be expected to create an annular zone of confusion, so that light from two different directions in o…
A five-year retrospective study of the epidemiological characteristics and visual outcomes of patients hospitalized for ocular trauma in a Mediterran…
2008
Abstract Background To determine the epidemiological characteristics and visual outcome of ocular trauma in southern Italy. Methods All cases of ocular trauma admitted to Department of Ophthalmology of Palermo University, Italy, from January 2001–December 2005 were retrospectively reviewed for open- or closed-globe injury (OGI or CGI). Data extracted included age, sex, residence, initial and final visual acuity (VA), cause and treatment of injury, hospitalization. The injuries were classified by Ocular Trauma Classification System (OTCS) and Birmingham Eye Trauma Terminology (BETT). We also referred to the Ocular Trauma Score (OTS) in evaluating the final visual outcome. Results Of the 298 …
Five-year functional outcomes and vault of -20 diopter myopic phakic intraocular lens implantation.
2015
Purpose To evaluate refractive and visual outcomes and complications associated with phakic intraocular lens (pIOL) implantation to correct high myopia. Settings Fernandez-Vega Ophthalmological Institute, Oviedo, Spain. Design Retrospective observational case series. Methods Uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA), refraction, vault, and adverse effects were evaluated after 5 years with Visian ICMV4 pIOL. Results Mean spherical equivalent (SE) dropped from −18.32 ± 2.37 diopters (D) preoperatively to −0.88 ± 0.52D 5 years postoperatively; 61% of eyes were within ±0.75 D of the target. The mean Snellen decimal CDVA and UDVA were 0.73 ± 0.23 and 0…
Prevalence of cataract after collagen copolymer phakic intraocular lens implantation for myopia, hyperopia, and astigmatism
2015
Purpose To evaluate the prevalence of cataract after Implantable Collamer Lens phakic intraocular lens (pIOL) implantation with different models at different ages and for different refractive powers. Setting Fernandez-Vega Ophthalmological Institute, Oviedo, Spain. Design Retrospective nonrandomized clinical study. Methods The pIOL (models V4, V4b, or V4c) was implanted in all cases. Results The study included 3420 eyes (1898 patients). The mean patient age at surgery was 31.2 years ± 6.4 (SD) (range 18 to 50 years) and the mean spherical refractive error, −7.27 ± 5.24 diopters (D) (range −26.5 to 12.5 D). Twenty-one eyes (0.61%) of 15 patients had pIOL explantation (all model V4) because c…
Collagen copolymer posterior chamber phakic intraocular lens supported by the ciliary sulcus to treat myopia: One-year follow-up
2014
Purpose To evaluate the predictability, stability, safety, and efficacy of Visian V4b Implantable Collamer Lens phakic intraocular lens (pIOL) implantation to treat varying degrees of myopia. Setting Fernandez-Vega Ophthalmological Institute, Oviedo, Spain. Design Prospective nonrandomized clinical study. Methods The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, pIOL vault, and adverse effects were evaluated 12 months postoperatively. Results The study enrolled 121 eyes (68 patients). The mean spherical equivalent decreased from −8.61 diopters (D) ± 3.41 (SD) (range −18.75 to −2.25 D) preoperatively to −0.18 ± 0.29 D (range −1.25 to 0.50 D) 12 months postoper…
Clinical Impact of a Spontaneous Decentration of a Phakic Refractive Lens
2011
PURPOSE To evaluate the clinical impact and possible causes of a spontaneous decentration of a phakic refractive lens (PRL) implanted in a highly myopic eye, and analyzing the visual, refractive, and aberrometric outcome as well as the possible causes for this phenomenon. METHODS The description of a case of bilateral high myopia corrected by implantation with the phakic intraocular lens (pIOL) PRL (Carl Zeiss Meditec, Germany) is presented and documented. Both eyes had similar anatomical configuration, and therefore, a pIOL (Model 101) with the same size was implanted without any associated intraoperative complication. Clinical outcomes were evaluated during a 3-month follow-up. RESULTS Im…
Iris-fixated toric phakic intraocular lens for myopic astigmatism
2011
Purpose To evaluate the efficacy, predictability, safety, stability, and complications of the Artiflex toric iris-fixated phakic intraocular lens (pIOL) for myopic astigmatism. Setting Private practice surgery centers, Valencia and Terrassa, Spain. Design Cohort study. Methods At 12 months, refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, complications, pIOL misalignment, and endothelial cell count (ECC) were evaluated. Indices of success and misalignment were calculated using vector analysis. Results The study enrolled 42 eyes in 25 patients aged 21 to 39 years. The mean spherical equivalent decreased from −8.85 diopters (D) ± 2.71 (SD) to −0.37 ± 0.46 D, with …
On-eye optical quality of daily disposable contact lenses for different wearing times
2012
Purpose To quantify the optical quality of various daily disposable contact lenses in vivo and to ascertain its variation in terms of wearing time by means of objective non-invasive determination of wavefront patterns. Methods The crx1 adaptive-optics system was used to measure the wavefront aberrations in 15 myopic eyes before and at 2-h intervals after contact lens fitting, over a 12-h wearing period. Seven types of contact lenses having different material, water content and lens design were evaluated in this study: Dailies Total1, Dailies AquaComfort Plus, Proclear 1 Day, 1-Day Acuvue TruEye, 1-Day Acuvue moist, SofLens daily disposable and Clariti 1-Day. The aberration data were analyse…
Crystalens HD Intraocular Lens Analysis Using an Adaptive Optics Visual Simulator
2013
PURPOSE To compare visual and optical quality of the Crystalens HD intraocular lens (IOL) with that of a monofocal IOL. METHODS The wavefront aberration patterns of the monocular Akreos Adapt AO IOL and the single-optic accommodating Crystalens HD IOL were measured in a model eye. The Crystalens IOL was measured in its nonaccommodative state and then, after flexing the haptic to produce 1.4 mm of movement, in its accommodative state. Using an adaptive optics system, subjects' aberrations were removed and replaced with those of pseudophakes viewing with either lens. Monocular distance visual acuity (DVA) at high (100%), medium (50%), and low (10%) contrast and contrast sensitivity (CS) were …