Search results for "Aberrations of the eye"
showing 10 items of 11 documents
Changes in higher-order aberrations after implantation of a foldable iris-claw lens in myopic phakic eyes
2006
Purpose To evaluate the change in higher-order aberrations (HOAs) after implantation of a foldable iris-claw phakic intraocular lens (pIOL) in myopic eyes. Setting Department of Ophthalmology, Johannes Gutenberg-University, Mainz, Germany. Methods This prospective nonrandomized comparative self-controlled trial included 41 eyes that had implantation of a foldable iris-claw pIOL between July 2003 and November 2004. All patient data for HOAs (Zernike coefficient) were measured and calculated using the same pupil size preoperatively and postoperatively, and the root-mean-square (RMS) wavefront error was calculated. Examinations were performed preoperatively as well as 1 week and 3, 6, and 12 m…
Optical quality of hyperopic and myopic phakic intraocular lenses
2013
Aims: To assess and compare the optical quality of the myopic and hyperopic implantable collamer lens (ICL) from its wavefront aberrations for different powers and pupil diameters. Settings and Design: Prospective study. Material and Methods: The wavefront aberrations of two myopic (−3 and −6 diopters (D)) and two hyperopic V4b ICLs (+3 and +6D) were measured in vitro . To assess and compare the optical quality of different powers of ICLs, we analyzed the root mean square (RMS) of total higher order aberrations (HOAs), trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration at 3- and 4.5-mm pupil. In addition, the point spread functions (PSFs) of each ICL evaluated were ca…
Dynamic accommodation without feedback does not respond to isolated blur cues
2016
Highlights • A new methodology is used to study a potential cue for dynamic accommodation. • We show that human accommodation is not driven correctly by defocus alone. • Accommodation is most efficient using changes in stimulus vergence with feedback.
A pilot study on the differences in wavefront aberrations between two ethnic groups of young generally myopic subjects
2008
A comparative population-based cross-sectional study design was used to examine the prevalence of wavefront patterns in two different ethnic groups, and the relationship of these patterns with ocular biometrics and gender. The Shin–Nippon SRW5000 open field autorefractor, the Wavefront Analysis Supported Customized Ablation (WASCA) wavefront analyser and the IOLMaster were used to determine wavefront aberrations, mean spherical equivalent (SE) refractive error and axial length (AL). Seventy-four eyes from 74 young healthy subjects (44 British Asians, 30 Caucasians; 36 men, 38 women; mean age 22.51 ± 3.89 years) with mean SE averaging )1.90 ± 2.76 D (range )10.88 to +2.19 D) were examined. R…
Optical Quality Comparison of Conventional and Hole-Visian Implantable Collamer Lens at Different Degrees of Decentering
2012
To compare the optical quality of implantable Collamer lens (ICL) with and without central hole (Hole ICL and conventional ICL) at different degrees of decentering.Experimental laboratory investigation.Wavefront aberrations of the -3, -6, and -12 diopter (D) V4b and -3, -6, and -12 D V4c ICLs were measured in 3 conditions-centered and decentered 0.3 and 0.6 mm-at 3-mm and 4.5-mm pupils. The root mean square of total higher order aberrations, trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration were evaluated. In addition, point spread function and simulated retinal images of ICLs were calculated from the wavefront aberrations for each ICL and all conditions of decenteri…
Corneal and Refractive Astigmatism in Adults: A Power Vectors Analysis
2009
Purpose. In this article, we examine the relationship between corneal and refractive astigmatism (including with the rule, against-the-rule, and oblique astigmatism) in an adult population using power vectors. Methods. Refractive and keratometric measures of astigmatism were conducted on right eyes of 105 white subjects aged 18 to 59 years. We performed a linear regression of refractive astigmatic error on corneal astigmatism, using the J0 and J45 components of the astigmatism. Results. We obtained a statistically significant regression relationship between the corneal (C) and refractive (R) astigmatism for both J0 and J45 components, namely, RJ0 = 1.07 × CJ0 − 0.28; and RJ45 = 1.46 × CJ45 …
The effect of simulated normal and amblyopic higher-order aberrations on visual performance.
2012
Purpose To study the effect of simulated amblyopic and normal higher-order aberrations on visual performance of normal eyes. Methods To assess visual function, an adaptive optics visual simulator was used to compensate volunteers' ocular aberrations and simulate the wavefront aberration patterns found in healthy and amblyopic eyes in 7 healthy individuals. Visual acuity for high (100%), medium (50%), and low (10%) contrast and contrast sensitivity at 10, 20, and 25 cycles per degree (cpd) were measured after simulation of both pattern aberrations. The modulation transfer function and the point spread function were computed based on the aberration data. All measures were taken for 3 and 5.5 …
The posterior chamber phakic refractive lens (PRL): a review
2012
Implantation of phakic intraocular lenses (pIOLs) is a reversible refractive procedure, preserving the patient’s accommodative function with minimal induction of higher order aberrations compared with corneal photoablative procedures. Despite this, as an intraocular procedure, it has potential risks such as cataracts, chronic uveitis, pupil ovalization, corneal endothelial cell loss, pigmentary dispersion syndrome, pupillary block glaucoma, astigmatism, or endophthalmitis. Currently, only two models of posterior chamber pIOLs are commercially available, the implantable collammer lens (STAAR Surgical Co.) and the phakic refractive lens (PRL; Zeiss Meditec). The number of published reports on…
Detection of wave aberrations in the human eye using a retinoscopy-like technique
2006
The influence of optical aberrations on the retinoscopic reflex is theoretically analyzed from a geometrical point of view. The relationship between the wave aberrations to the ray aberrations is applied to explain the appearance of the retinoscopic patterns for different types of ocular aberrations. Several schematic models of the human eye are tested numerically, showing that a careful retinoscopic examination can detect the usual eye aberrations.
Comparison of higher order aberrations measured by NIDEK OPD-Scan dynamic skiascopy and Zeiss WASCA Hartmann-Shack aberrometers.
2008
<h4>PURPOSE</h4><p>To compare the measurement of wavefront aberrations in non-cyclopleged human eyes with Hartmann-Shack and dynamic skiascopy wavefront analyzers.</p> <h4>METHODS</h4><p>Eighty eyes of 40 healthy young adults (19 men, 21 women; mean age 20.8±2.5 years) with refractive errors ranging from +1.50 to –9.75 diopters (D) sphere and up to 1.75 D cylinder (mean spherical equivalent refraction –2.12±2.69 D) were examined with the Zeiss/Meditec WASCA and NIDEK OPD-Scan wavefront analyzers and with the Nippon SRW5000 binocular, open-field autorefractor without the instillation of antimuscarinic agents. Three measurements were taken with each s…