Search results for " astigmatism"
showing 10 items of 25 documents
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…
Effects of Superficial Keratectomy in Peripheral Hypertrophic Subepithelial Corneal Opacification on Front and Back Corneal Astigmatism
2020
To evaluate changes of anterior and posterior corneal astigmatism after superficial keratectomy in peripheral hypertrophic subepithelial corneal opacification (PHSCO). Patients with PHSCO, who had ...
Refractive Lens Exchange with Foldable Toric Intraocular Lens
2009
To assess visual and refractive outcomes, and rotational stability after refractive lens exchange (RLE) with toric intraocular lens (IOL) implantation to correct ametropia and preexisting astigmatism.Prospective, nonrandomized, observational case series (self-controlled).This prospective, nonrandomized, and self-controlled study included 32 eyes of 19 consecutive patients with more than 1.00 diopter (D) of preexisting corneal astigmatism having RLE with AcrySof Toric IOL implantation (Alcon Laboratories Inc, Fort Worth, Texas, USA). Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), refractive sphere, and keratometric and refractive cylinder were recorded preoperatively …
Behaviour of the phakic iris-claw intraocular lens (Artisan /Verisyse) during accommodation: an optical coherence biometry study.
2007
Purpose To evaluate variations in the position of the phakic iris claw lens (Artisan®, Verisyse®) and the natural crystalline lens during the accommodation process. Methods We measured changes in position of the iris claw lens and the crystalline lens during the accommodation using optical coherence biometry (AC Master®/Carl Zeiss Meditec, Germany) in 17 patients (28 eyes) with a phakic iris claw lens implanted for high myopia and/or myopic astigmatism. Accommodative effort was obtained using an internal optical target within the measuring device. Results There was a forward shift of the phakic iris claw lens with a mean of 70 μm (8–178 μm) of the optical path length (OPL). At the same time…
Corneoscleral contact lenses for visual rehabilitation after keratoplasty surgery.
2019
Abstract Purpose To report the use of corneoscleral lenses (CSL) in keratoconus patients who were unsatisfied with their visual outcomes after keratoplasty surgery. Methods Eleven consecutive cases with unsatisfactory vision with spectacles, due to irregular astigmatism, preferred to try CSL before SL due to handling or economic issues. An eye examination included refraction and visual acuity assessment, anterior eye biomicroscopy, ocular fundus examination, corneal topographic analysis, endothelial-cell count (ECC) and evaluation of corneal biomechanical parameters (corneal resistance factor, CRF; corneal hysteresis, CH; corneal-compensated intraocular pressure, IOPcc). The fitting process…
Trifocal toric intraocular lenses in eyes with low amount of corneal astigmatism.
2020
Aim To evaluate the refractive and visual outcomes following cataract surgery and implantation of a trifocal toric intraocular lens (IOL) in eyes with low degrees of corneal astigmatism. Methods Twenty-six eyes of 22 patients who underwent implantation a trifocal toric IOL (FineVision PODFT, PhysIOL s.a., Liege, Belgium) were enrolled. Phacoemulsification with femtosecond laser, capsular tension ring insertion and intraoperative aberrometry were performed in all cases. All IOLs used showed a cylinder power of 1.00 D. Main outcome measures were refractive error and corrected-distance visual acuity (CDVA) and uncorrected-distance visual acuity (UDVA) values. Eyes were evaluated at 4mo post-su…
Prevalence of corneal astigmatism before cataract surgery.
2008
To analyze the prevalence and presentation patterns of corneal astigmatism in cataract surgery candidates.University of Valencia, Valencia, Spain.Refractive and keratometric values were measured before surgery in patients having cataract extraction. Descriptive statistics of refractive and keratometric cylinder data were analyzed and correlated by age ranges.Refractive and keratometric data from 4,540 eyes of 2,415 patients (mean age 60.59 years +/- 9.87 [SD]; range 32 to 87 years) differed significantly when the patients were divided into 10-year subsets. There was a trend toward less negative corneal astigmatism values, except the steepest corneal radius and the J(45) vector component, in…
Visual acuity with computer simulated and lens-induced astigmatism
2014
[EN] The relationship between spherical and astigmatic refractive errors and their associated visual acuity is investigated in this work by means of two different approaches. In the first one, different refractive errors were induced in normal subjects by trial lenses. In the second one, defocused images were simulated numerically by the optical transfer function of a model eye and then judged by the same subjects. The amount of defocus (measured in terms of the modulus of the dioptric power vector) necessary to reduce the visual acuity to 0.1 logMAR and to 0.4 logMAR was computed with each method and then compared. We found that the visual system is clearly more tolerant to lens-induced de…
Astigmatism among myopics and its changes from childhood to adult age: a 23‐year follow‐up study
2014
Purpose To study the prevalence of and changes in astigmatism from the onset of myopia at school age. Methods Two hundred and forty 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. Three annual examinations with subjective cycloplegic refraction were performed for 237–238 subjects. Subsequent examinations were performed at the mean ages of 23.2 and 33.9 years for 178 and 163 subjects, and the last examination, including data from prescriptions of different ophthalmologists, for 32 subjects. Corneal topography was studied at baseline, at the 3-year follow-up and at t…
Heritability of corneal refraction and corneal astigmatism: a population-based twin study among 66- to 79-year-old female twins.
2012
. Purpose: To examine the heritability of corneal refraction power (CR) and corneal astigmatism (AST) in older women. Methods: Corneal refraction and AST were measured by IOL master in 52 monozygotic (MZ) and 47 dizygotic (DZ) female twin pairs aged 66–79 years. The relative contribution of genetic and environmental factors to individual differences in CR was estimated by applying an independent pathway model to the twin data and AST by intraclass correlations (ICC). Results: For the right eye, mean CR was 44.58 dioptres (D) (standard deviation (SD) ±1.28) When comparing CR of the right and left eye between MZ and DZ, no significant difference was found. Mean AST was 0.77 D (SD ±0.44) wi…