Meridional Subjective Refraction With Dynamic Optometer Instrumentation
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Meridional Subjective Refraction With Dynamic Optometer Instrumentation
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Author : Denis Humphreys
language : en
Publisher:
Release Date : 1974
Meridional Subjective Refraction With Dynamic Optometer Instrumentation written by Denis Humphreys and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1974 with Eye categories.
Evaluation Of Meridional Refraction Techniques
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Author : Jennifer Nicole Chlam
language : en
Publisher:
Release Date : 2022
Evaluation Of Meridional Refraction Techniques written by Jennifer Nicole Chlam and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with Eye categories.
Purpose: To evaluate subjective and objective refraction methods based on oriented grating targets. Methods: Subjective and objective meridional refraction was performed on 21 young normally-sighted subjects. Both the subjective and objective refraction methods were performed with and without cycloplegia. Targets for refraction were Gaussian-attenuated square wave gratings at four orientations (00, 450, 900, 1350), with a bar width equal to 2x the subject’s threshold letter size (i.e. for 20/20, 10 minarc/bar width, or 3 cycles/degree). The endpoint of the refraction was the spherical lens power to achieve maximum grating contrast. Lens power at each grating orientation was determined twice, and the sphero-cylindrical correction was derived from the dioptric power for those four orientations. The objective refractive correction was based on a measurement of ocular aberrations. In both the cyclopleged and non-cyclopleged conditions, aberration coefficients were transformed from those for the measured pupil diameter to a 3.5 mm pupil. As in the subjective method, the dioptric power to maximize grating contrast was found for each orientation, and the sphero-cylindrical correction was derived from those powers. Visual acuity was measured with the result of each refraction using an adaptive, maximum-likelihood method. Visual acuities with the result of the cycloplegic refraction were measured at a second visit, at least one day after the refraction visit. Results: Intra-session repeatability of M, J0, and J45 of dry subjective refraction was not significantly different from those found in a previous similar study (2-sample Kolmogorov-Smirnov test, p>.10). The standard deviations of M, J0, and J45 were 0.20D, 0.29D, and 0.22D, respectively, and is comparable to repeatability of standard methods of subjective refraction. Agreement between the different types of refraction was evaluated by examining differences in M, J0, J45, and in total dioptric power. Wet and dry objective refraction agreed most closely: the median dioptric difference in 3D dioptric power space was 0.16D. Pairwise comparison across all refraction methods had median values of at least twice that value. Mean visual acuity achieved with the results of each type of refraction ranged from logMAR -0.15 for dry subjective refraction to -0.19 for dry objective refraction. Differences in visual acuity between all four refraction methods were not significantly different (2-way ANOVA, p>0.5). Conclusions: In this sample of young normal subjects, these refraction methods based on oriented meridional targets yield results with repeatability similar to published values for standard methods of refraction. In future studies, we will examine the performance of these refraction methods in more highly aberrated eyes. We hypothesize that the subjective task could be simpler, and therefore more consistent, with these oriented targets, as the judgement is primarily of grating contrast, and is less confounded by changes in contrast and phase at multiple simultaneous orientations.
New Method Of Subjective Refraction Involving Identical Technics In Static And Dynamic Tests
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Author : Matthew Luckiesh
language : en
Publisher:
Release Date : 1940
New Method Of Subjective Refraction Involving Identical Technics In Static And Dynamic Tests written by Matthew Luckiesh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1940 with categories.
Cumulated Index Medicus
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Author :
language : en
Publisher:
Release Date : 1997
Cumulated Index Medicus written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997 with Medicine categories.
Clinical Refraction Guide
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Author : Ajay Kumar Bhootra
language : en
Publisher: Jaypee Brothers Medical Publishers
Release Date : 2019-06-30
Clinical Refraction Guide written by Ajay Kumar Bhootra and has been published by Jaypee Brothers Medical Publishers this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-06-30 with Medical categories.
Retinoscopy is an eye exam that determines the refractive error of the eye (long sighted, short sighted, astigmatism). A refraction test indicates the strength of the prescription needed for glasses or contact lenses. The new edition of this book provides a concise overview of clinical refraction. Presented in an easy to read format, it is divided into two main sections. The first part explains basic clinical procedures for routine refraction, beginning with an introduction to instruments and the procedure, followed by aspects of the test for different disorders including myopia (short sightedness), astigmatism, keratoconus and refraction in children. Section two provides in depth discussion on retinoscopy and correct use of the retinoscope. The second edition has been fully revised and updated to explain the latest advances in the field, and is further enhanced by clinical images and figures. Key points Practical guide to clinical refraction and retinoscopy Fully revised and updated second edition Explains basic procedures and instruments for refraction test and refraction in different ophthalmic disorders Previous edition (9789351520634) published in 2014
Myopia And Nearwork
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Author : Mark Rosenfield
language : en
Publisher: Butterworth-Heinemann Medical
Release Date : 1998
Myopia And Nearwork written by Mark Rosenfield and has been published by Butterworth-Heinemann Medical this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with Medical categories.
This book combines theory, practice and research into the field in one complete volume.
Optics Of The Human Eye
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Author : David A. Atchison
language : en
Publisher: Butterworth-Heinemann Medical
Release Date : 2000
Optics Of The Human Eye written by David A. Atchison and has been published by Butterworth-Heinemann Medical this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with Medical categories.
This text describes the optical structures and optical properties of the human eye. It is divided into five sections, covering topics such as basic optical structure of the human eye and image formation and refraction of the eye.
Borish S Clinical Refraction E Book
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Author : William J. Benjamin
language : en
Publisher: Elsevier Health Sciences
Release Date : 2006-10-13
Borish S Clinical Refraction E Book written by William J. Benjamin and has been published by Elsevier Health Sciences this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006-10-13 with Medical categories.
Now updated and expanded to cover the latest technologies, this full-color text on clinical refraction uses an easy-to-read format to give optometry students and practitioners all the important information they need. Also covers a wide range of other aspects of the eye exam, including anterior and posterior segment evaluations, contact lens, ocular pharmacology, and visual field analysis. Four new chapters cover wavefront-guided refraction, optical correction with refractive surgeries, prosthetic devices, and patients with ocular pathology. Offer precise, step-by-step how-to's for performing all of the most effective refractive techniques. Presents individualized refractive approaches for the full range of patients, including special patient populations. Contriubtors are internationally recognized, leading authorities in the field. New full-color design with full-color images throughout. Completely updated and expanded to include current technologies. A new chapter on Optical Correction with Refractive Surgeries, including keratoplasty, traditional refractive surgeries (e.g. LASIK and PRK), crystalline lens extraction with and without pseudophakia, the new presbyopic surgery, etc. A new chapter on Wavefront Guided Refraction provides information on the advantages and limitations the Hartmann-Shack Method for objective refraction plus aberrometry and the refraction and the use of in the correction of the eye with spectacles, contact lenses, and refractive surgery. A new chapter on Patients with Ocular Pathology reflects the most current knowledge of patients with ocular pathologies. Provides information on Optical Correction with Prosthetic Devices, including corneal onlays, stromal implants, phakic intraocular lenses, etc. Includes new chapters and/or discussions on such topics as: Aberrations of the Eye, Refractive Consequences of Eye Pathology, Diagnosis and Treatment of Dry Eye, Diagnosis of Pathology of the Anterior Segment, Diagnosis of Glaucoma, and Diagnosis of Pathology of the Posterior Segment. Visual Acuity chapter expanded to include the effect of refractive error on visual acuity and statistics on how much of a change in visual acuity is significant. Objective Refraction, Corneal Topography, and Visual Field Analysis chapters include the addition of new electro-optical and computer techniques and equipment. Chapters on Multifocal Spectacle Lenses and Contact Lenses now cover newer progressive addition lenses and contact lenses that are now on the market. Electrodiagnosis chapter revised to take a more clinical approach.
Clinical Optics
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Author : Andrew R. Elkington
language : en
Publisher: Wiley-Blackwell
Release Date : 1999-08-25
Clinical Optics written by Andrew R. Elkington and has been published by Wiley-Blackwell this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999-08-25 with Medical categories.
Written to help trainee ophthalmologists, this textbook is now the recognised text on optics for the examinations of the Royal College of Ophthalmologists and the Royal Surgical Colleges. It approaches the subject from first principles and assumes no previous knowledge of optics. The book has been kept as simple as possible and is liberally complemented with diagrams designed to be easily understood and memorised. Only the most fundamental and clinically useful mathematical formulae are quoted, and the optical principles are applied to clinical situations. Ophthalmology examinations have changed substantially since the last edition was written and a total rewrite of this essential guide has become necessary. The third edition has been made more comprehensive and detailed to keep up with these changes and incorporates three new chapters: refractive surgery, contact lenses and lasers. Other new material includes photometry, visual acuity, contrast sensitivity, colour vision, absorptive lenses, fluorescence, ultrasound, and the specular microscope.
Astigmatism
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Author : Michael Goggin
language : en
Publisher: BoD – Books on Demand
Release Date : 2012-02-29
Astigmatism written by Michael Goggin and has been published by BoD – Books on Demand this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-02-29 with Medical categories.
This book explores the development, optics and physiology of astigmatism and places this knowledge in the context of modern management of this aspect of refractive error. It is written by, and aimed at, the astigmatism practitioner to assist in understanding astigmatism and its amelioration by optical and surgical techniques. It also addresses the integration of astigmatism management into the surgical approach to cataract and corneal disease including corneal transplantation.