Search results for "refractive error"
showing 10 items of 125 documents
The effect of fractal contact lenses on peripheral refraction in myopic model eyes.
2014
Purpose: To test multizone contact lenses in model eyes: Fractal Contact Lenses (FCLs), designed to induce myopic peripheral refractive error (PRE). Methods: Zemax ray-tracing software was employed to simulate myopic and accommodation-dependent model eyes fitted with FCLs. PRE, defined in terms of mean sphere M and 90–180 astigmatism J180, was computed at different peripheral positions, ranging from 0 to 35 in steps of 5, and for different pupil diameters (PDs). Simulated visual performance and changes in the PRE were also analyzed for contact lens decentration and model eye accommodation. For comparison purposes, the same simulations were performed with another commercially available conta…
Anisometropia of spherical equivalent and astigmatism among myopes: a 23-year follow-up study of prevalence and changes from childhood to adulthood.
2017
Purpose To study anisometropia of spherical equivalent and astigmatism from the onset of myopia at school age to adulthood. Methods A total of 240 myopic schoolchildren (mean age 10.9 years), with no previous spectacles, were recruited during 1983–1984 to a randomized 3-year clinical trial of bifocal treatment of myopia. Examinations with subjective cyclopedic refraction were repeated 3 years later (follow-up 1) for 238 subjects and thereafter at the mean ages of 23.2 (follow-up 2) and 33.9 years (follow-up 3) for 178 and 134 subjects. After exclusions, the 102 subjects who attended all three follow-ups were included in the analyses. Corneal refractive power and astigmatism and anterior cha…
Associations of Children’s Close Reading Distance and Time Spent Indoors with Myopia, Based on Parental Questionnaire
2022
Purpose: To study the association of parents’ reports about their children’s near work and outdoor habits with myopia in their children. Methods: Data from a questionnaire study conducted in 1983 among Finnish schoolchildren were reanalyzed. Vision screening had been performed for all the schoolchildren (n = 4961) in the 1st, 5th, and 8th grades (7-, 11-, and 15-year-olds) in an area of Central Finland. The questionnaire, including information about myopia, was returned by 4305 (86.7%) participants. Items concerned parents’ estimates of their child’s habitual reading distance, time spent indoors as compared with age peers, daily near work, outdoors time, and parents&…
Prevalence of refractive errors in the European adult population: the Gutenberg Health Study (GHS).
2014
Objective To study the distribution of refractive errors among adults of European descent. Design Population-based eye study in Germany with15 010 participants aged 35–74 years. Methods The study participants underwent a detailed ophthalmic examination according to a standardised protocol. Refractive error was determined by an automatic refraction device (Humphrey HARK 599) without cycloplegia. Definitions for the analysis were myopia +0.5 D, astigmatism >0.5 cylinder D and anisometropia >1.0 D difference in the spherical equivalent between the eyes. Exclusion criterion was previous cataract or refractive surgery. Results 13 959 subjects were eligible. Refractive errors ranged from −21.5 to…
Long-term results of surgical treatment of high myopia with Worst-Fechner intraocular lenses
1995
Abstract This retrospective study evaluated the results in 90 eyes that had a minus-power anterior chamber intraocular lens implanted to correct high myopia. Preoperative myopia ranged from −7.00 to −24.00 D. Postoperative spherical equivalent was −0.50 D; 80.5% of eyes were within 1.00 D of emmetropia. Two years postoperatively, no cataract formation, retinal detachment, glaucoma, or significant endothelial damage had occurred. We conclude that minus-power lenses can rapidly, safely, and predictably correct high myopia in phakic patients.
Rate of Cataract Formation in 343 Highly Myopic Eyes After Implantation of Three Types of Phakic Intraocular Lenses
2004
ABSTRACT PURPOSE: To assess the feasibility of using phakic intraocular lenses (PIOL) to treat high myopia, and evaluate the incidence of cataract, comparing three different lens types. METHODS: From 1989 to 2002, we implanted three different phakic intraocular lenses (PIOL) in 343 eyes of 232 patients; 231 eyes recieved an Ophtec (Worst-Fechner model, iris-claw), 89 an Adatomed (silicone posterior chamber), and 23 a Staar (posterior chamber, models V2, V3, V4). Average follow-up was 96.2 months for the Ophtec group, 31.5 months for the Adatomed group, and 19.3 months for Staar group. Eyes that subsequently developed cataract were studied for clinical evolution and had PIOL explantation and…
Genome-wide meta-analyses of multiancestry cohorts identify multiple new susceptibility loci for refractive error and myopia
2013
Author version made available in accordance with the publisher's policy.
Repeatability of in vitro power profile measurements for multifocal contact lenses
2015
Abstract Purpose To evaluate the repeatability of an optical device (NIMO TR1504, Lambda-X, Belgium) for measuring multifocal contact lens power profiles. Methods The NIMO TR1504 was used to measure power profiles 30 times for each of 10 different contact lenses from 4 major companies. All contact lenses were labelled as −3 D for distance vision; half were for high addition and half for low addition. The optical zone in all measurements was set to 3-mm radius. For each lens, the median power profile and the residuals of the 30 measurements were calculated. The 95% confidence bands and two indices that summarize measurement errors were calculated: the repeatability limit and an index of repe…
Refraktiver Nutzen und inkrementelle Kosten der LASIK: Ergebnisse einer Kosten-Nutzen-Studie an zwei universitären LASIK-Zentren
2003
BACKGROUND No data is available to date on the cost effectiveness of laser in situ keratomileusis (LASIK) with regard to the German-speaking health care system. Hence we compared the clinical outcome and cost data of two German LASIK centres in respect of procedure cost effectiveness from the patient perspective. MATERIAL AND METHODS A retrospective cohort study was implemented at the University Hospitals of Mainz and Mannheim. Data on refractive outcome were obtained from the LASIK centres' patient documentation, cost data on the surgery as well as on eyeglasses etc. before and after the surgery were obtained from patient interviews. The primary endpoint of this investigation was the indiv…
Visual defects in subjects with Down’s syndrome
1995
Because the incidence of other visual defects is much higher in cases of Down’s syndrome than in individuals with other forms of retardation (Gardiner, 1967; Aitchison et al., 1990), we tested the color vision of a population of Down’s syndrome patients, using Ishihara plates and the Davico anomaloscope. The Down’s syndrome group had a significantly higher proportion of color deficiencies than either normal controls or a matched mentally retarded population. Refractive errors were corrected with static retinoscopy, and spatial contrast sensitivity was measured with the Vistech test.