نتایج جستجو برای: order aberrations

تعداد نتایج: 923530  

Journal: :Vision Research 2006
J. S. McLellan P. M. Prieto S. Marcos S. A. Burns

Wave aberrations degrade the optical quality of the eye relative to the diffraction limit, but there are situations in which having slightly aberrated optics can provide some relative visual benefits. This fact led us to consider whether interactions among aberrations in the eye's wavefront produce an advantage for image quality relative to wavefronts with randomized combinations of aberrations...

Journal: :بینا 0
فرید کریمیان f karimian ophthalmic research center, shahid beheshti university of medical sciences, tehran, iranدانشگاه علوم پزشکی شهید بهشتی سپهر فیضی s feizi ophthalmic research center, shahid beheshti university of medical sciences, tehran, iranدانشگاه علوم پزشکی شهید بهشتی محمدرضا جعفری نسب mr jafarinasab ophthalmic research center, shahid beheshti university of medical sciences, tehran, iranدانشگاه علوم پزشکی شهید بهشتی نسیم فرد اسماعیل پور n fard esmaeil pour ophthalmic research center, shahid beheshti university of medical sciences, tehran, iranدانشگاه علوم پزشکی شهید بهشتی سعید انصاری s ansari ophthalmic research center, shahid beheshti university of medical sciences, tehran, iranکلینیک نگاه آزاده دوزنده a doozandeh ophthalmic research center, shahid beheshti university of medical sciences, tehran, iranدانشگاه علوم پزشکی شهید بهشتی

purpose: to compare visual outcomes and changes in high-order aberrations (hoas) following conventional versus customized photorefractive keratectomy (prk). methods: in this clinical trial, 58 eyes of 29 patients underwent myopic prk using the technolas 217z excimer machine. after comprehensive evaluation for refractive surgery, one eye of each participant randomly received conventional ablatio...

Journal: :Journal of refractive surgery 2005
Susana Marcos Sergio Barbero Ignacio Jiménez-Alfaro

PURPOSE To compare experimental optical performance in eyes implanted with spherical and aspheric intraocular lenses (IOLs). METHODS Corneal, total, and internal aberrations were measured in 19 eyes implanted with spherical (n=9) and aspheric (n=10) IOLs. Corneal aberrations were estimated by virtual ray tracing on corneal elevation maps, and total aberrations were measured using a second-gen...

Journal: :Journal of refractive surgery 2000
D Williams G Y Yoon J Porter A Guirao H Hofer I Cox

There is currently considerable debate concerning the visual impact of correcting the higher order aberrations of the eye. We describe new measurements of a large population of human eyes and compute the visual benefit of correcting higher order aberrations. We also describe the increase in contrast sensitivity when higher order aberrations are corrected with an adaptive optics system. All thes...

2011
Joseph Colin

The use of wavefront-guided algorithms for treatment has increased over the past decade with estimates that up to 50 percent of all laser in situ keratomileusis (LASIK) procedures are now performed with this approach1. Although originally intended to correct higher order aberrations, the use of wavefront-guided algorithms, particularly those with iris-registration and tracking, have been shown ...

Journal: :Journal of refractive surgery 2006
Prema Padmanabhan Geunyoung Yoon Jason Porter Srinivas K Rao J Roy Mitalee Choudhury

PURPOSE To characterize and measure the ocular aberrations in eyes implanted with monofocal intraocular lenses (IOLs) and to study any correlation between postoperative aberrations and surgical factors. METHODS A Tscherning aberroscope was used to measure the wavefront aberrations of 62 eyes that had undergone phacoemulsification with the implantation of foldable monofocal Acrysof MA60BM IOLs...

Journal: :Bulletin de la Societe belge d'ophtalmologie 2006
S Marcos

This paper addresses the concept, measurement and applications of wave aberrations. The ocular optics is not perfect. Apart from conventional low order aberrations (such as defocus and astigmatism) retinal images are degraded by other high order aberrations. Aberrometers typically measure ray deviations at the retinal plane, as a function of pupil position, i.e. local derivatives of the wave ab...

Journal: :Journal of the Optical Society of America. A, Optics, image science, and vision 2002
Geun-Young Yoon David R Williams

The development of technology to measure and correct the eye's higher-order aberrations, i.e., those beyond defocus and astigmatism, raises the issue of how much visual benefit can be obtained by providing such correction. We demonstrate improvements in contrast sensitivity and visual acuity in white light and in monochromatic light when adaptive optics corrects the eye's higher-order monochrom...

Journal: :Ultramicroscopy 2015
Ossi Lehtinen Dorin Geiger Zhongbo Lee Michael Brian Whitwick Ming-Wei Chen Andras Kis Ute Kaiser

Here, we present a numerical post-processing method for removing the effect of anti-symmetric residual aberrations in high-resolution transmission electron microscopy (HRTEM) images of weakly scattering 2D-objects. The method is based on applying the same aberrations with the opposite phase to the Fourier transform of the recorded image intensity and subsequently inverting the Fourier transform...

Journal: :International journal of ophthalmology 2015
Mohammad Taher Rajabi Sara Korouji Mahgol Farjadnia Mohammad Naderan Mohammad Bagher Rajabi Bahram Khosravi Seyed Mehdi Tabatabaie

AIM To compare higher order aberrations in two aspherical intraocular lenses (IOLs): Akreos advanced optics (AO) and Dr. Schmidt Microcrystalline 6125 aspheric anterior surface (MC6125AS) with each other. METHODS Forty eyes of 39 patients underwent phacoemulsification and Akreos AO and MC6125AS were implanted in their eyes in a random manner. Three months post-operatively, higher order aberra...

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