DOCSLIB.ORG

Refractive Surgery and Optical Aberrations

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Refractive Surgery and Optical Aberrations RefractiveRefractive SurgerySurgery andand OpticalOptical AberrationsAberrations Susana Marcos or more than a century there Measuring refractive- has been awareness of the fact surgery-induced change F that the eye is not a perfect of corneal aberrations optical system and that it suffers Computerized videokeratography from defects or optical aberrations — which measures the shape of the other than defocus and astigmatism. cornea, typically by analysis of the Attempts to measure the wave aber- distortion of concentric rings pro- ration of the human eye, i.e., phase jected on it—is routinely used in distortions at the plane of the pupil, clinics to evaluate surgical results date back to 1894. In recent years, (i.e., centration and location of the new terminology and new technolo- treatment zone and characteristic gy have invaded the field of refrac- patterns of what is known in clini- tive surgery and changed the way cal terms as irregular corneal astig- 2 ophthalmologists and optometrists matism). Applegate et al. and 3 look at the image-forming capabili- Oliver et al. used corneal elevation ties of ocular optics. Wave-front- Courtesy of Jesús Merayo and Raúl Martín. maps from commercial corneal sensing, aberrometers, high-order aberra- topographers to measure the changes tions, and Zernike polynomials are only a induced in the cornea by different types of few of the novelties that have recently optical quality of the human eye.1 Only refractive surgery; their findings show that entered the field. recently, however, as these procedures refractive surgery is generally followed by an Over the past two decades, several new have begun reaching a clinical population, increase in the amount of and an alteration methods have been developed to assess the has the instrumentation involved captured in the distribution of aberrations. the attention of refractive surgeons. For The corneal surface and the pattern of the compensation of refractive errors aberrations associated with any optical sys- (myopia, hyperopia, and astigmatism), tem are typically described as a polynomi- corneal refractive surgery has become a al expansion. The first-order terms corre- spond to a prismatic error; the second- popular alternative to wearing glasses or order terms to defocus and astigmatic contact lenses: the operation and recovery errors; third-order aberrations include are rapid and the procedures are constant- coma, in which a point source appears as a ly being perfected. The surgery alters the comatic shape; fourth-order aberrations curvature of the central area of the cornea, include spherical aberration, or increased reducing it in myopes and increasing it in focusing error as the pupil dilates. Studies hyperopes. From the lens designer’s point based on corneal topography show that, of view, it is clear that a change in only part for large pupils, corneal aberrations of the front surface of the cornea (the most increase by approximately a factor of 3. In refractive element of the ocular optical sys- addition, the distribution of aberrations tem) must modify the aberration pattern shifts from third-order dominance (coma- of the entire optical system. Particularly like) to fourth-order dominance (spheri- in the case of large pupils, an increase in cal). The dramatic increase in spherical Asymmetric optical aberrations—despite the correc- aberration is caused by a surgery-induced Symmetric tion of defocus and astigmatism—can change in corneal asphericity. Figure 1 frequently be associated with complaints shows the distribution of aberrations (in of halos and visual loss at night. Under- Figure 1. Distribution of corneal aberrations terms of variance) in normal eyes, and (symmetric versus asymmetric) for eyes before standing the change in aberrations in- one-year after radial keratotomy (RK), (pre-op) and one year after myopic RK, PRK and duced by standard refractive surgical pro- photorefractive keratectomy (PRK) , and LASIK. (Adapted from R. A. Applegate, H. C. cedures is important for assessment of laser in situ keratomileusis (LASIK). In Howland, and S. D. Klyce, Corneal Aberrations and how vision can be compromised after general, there is an increase in both third- Refractive Surgery in Customized Corneal Ablation: The surgery. It is essential to develop new abla- and fourth-order aberrations, and the Quest for Super Vision, Slack, Inc., N.J., in press. tion algorithms to overcome such prob- increase is correlated to a decrease in con- Courtesy of R.A. Applegate.) lems, and perhaps even improve vision. trast sensitivity. 22 Optics & Photonics News I January 2001 1047-6938/01/01/0022/4-$0015.00 © Optical Society of America REFRACTIVE SURGERY Measuring the aberrations point source are imaged sequentially Figure 2. In an ideal aberration-free eye, rays of the entire optical system as a laser beam scans the pupil through any pupil location would converge onto the same retinal location. The wave aberration Although refractive-surgery-induced opti- through different positions, and the would be flat, and the image of a point source cal changes occur on the cornea and the deviations of each image from the viewed through a large pupil would be an Airy 4-6 anterior corneal surface provides the main principal ray are analyzed ; disk. Real eyes are aberrated. Therefore, rays that contribution to refraction, corneal aberra- • Dresden wave-front analyzer (DWA), enter the eye through different pupil locations will tions are not sufficient to describe the in which the distortions of an array of hit the retina at different locations. The deviations overall optical quality of the eye. points projected in the pupil are ana- from the ideal are proportional to the local slope Experimental measurement of total lyzed7-9; of the wave aberration, which is distorted. The ocular aberrations is the most direct and • Spatially resolved refractometer (SRR), retinal image of a point source, (which can be sim- accurate way to evaluate the effects of a sequential procedure like the LRT, ulated from the wave aberration), is in general refractive surgery on global image quality, which differs from it in that the retinal asymmetric. Most instruments that measure the aberrations of the living human eye measure these and it can be more directly related to visu- displacements are assessed psychophys- al performance. Figure 2 shows the under- deviations by projecting light beams through the ically by the subject, who aligns the pupil and by analyzing the light returned from the 10 lying principle of most methods for mea- spots to a reference cross ; retina, or by psychophysical methods. surement of the wave aberration of the eye. • Hartmann–Shack wave-front sensor, in If the eye were perfect, or in other words which the wave front is sampled as it (a) only limited by diffraction (Fig. 2, upper exits the eye by a microlens array conju- (b) panel), rays that enter the eye through any gate to the pupil, and the deviations of pupil position would converge on the same the multiple images from the ideal focal retinal location. But in the presence of points are analyzed.11-13 aberrations, rays that enter the eye through different pupil positions deviate from the Figure 4 shows some examples of ideal location (or principal ray), as indicat- overall wave aberrations (third- through ed in Fig. 2, lower panel. These deviations seventh-order in the Zernike polynomial are proportional to the local derivatives of expansion) from a recent study by 6 (c) (d) the wave aberration; in other words, the Moreno-Barriuso et al. The results are rays are normal to the wave front that trav- for the same patients before and approx- els toward the retina. A perfect eye would imately one month after myopic LASIK have a wave aberration of zero; for an aber- surgery. The measurements were made rated eye, the wave aberration is the devia- with a laser ray-tracing system developed tion of the distorted wave front from the by Rafael Navarro and colleagues at the ideal sphere (see Fig. 2). With knowledge Consejo Superior de Investigaciones of the wave aberration, and therefore also Cientificas (CSIC) in Madrid, Spain. For of the pupil function of the entire optical each patient, the scale used to plot the wave Figure 3. Raw data using different methods to system, we can compute the point- aberration is the same before and after assess aberrations following refractive surgery. (a) spread-function (an Airy disk for the ideal surgery, and in all cases pupil diameter is LRT: series of retinal images of a point source system, but in general, an asymmetric 6.5-mm. Preoperative myopia ranged through different entry locations. This is a one- shape for the eye) and simulate the degra- between -13 and -2 diopters (D), and pre- month post-LASIK eye (Moreno-Barriuso et al.). dation of any visual scene projected on operative astigmatism was less than 2.5 D. (b) DWA: image of a grid distorted by the ocular the retina (Fig. 2). Preoperative aberration patterns showed a aberrations (courtesy of M. Mrochen). (c) large intersubject variability in terms of Hartmann–Shack wave-front sensor: image of a Several wave-front-sensing methods point source projected on the retina through a have been used to measure the ocular aber- both amount and distribution, but in gen- lenslet array in a two-month post-LASIK patient rations associated with refractive surgery. eral no deep valleys or high peaks were (courtesy of X. Hong and L. Thibos). (d) Spatially Figure 3 shows raw data from four of them: found. After surgery, a typical central resolved refractometer: sets of alignments (in the • Laser ray tracing (LRT) system, in island (associated with the ablation pat- form of a retinal spot diagram) from a post-LASIK which a series of aerial images of a tern) appears in all cases, with variable patient (courtesy of K.
Load more

Recommended publications
  • History of Refractive Surgery
    History of Refractive Surgery Refractive surgery corrects common vision problems by reshaping the cornea, the eye’s outermost layer, to bend light rays to focus on the retina, reducing an individual’s dependence on eye glasses or contact lenses.1 LASIK, or laser-assisted in situ keratomileusis, is the most commonly performed refractive surgery to treat myopia, hyperopia and astigmatism.1 The first refractive surgeries were said to be the removal of cataracts – the clouding of the lens in the eye – in ancient Greece.2 1850s The first lensectomy is performed to remove the lens 1996 Clinical trials for LASIK begin and are approved by the of the eye to correct myopia.2 Food & Drug Administration (FDA).3 Late 19th 2 Abott Medical Optics receives FDA approval for the first Century The first surgery to correct astigmatism takes place. 2001 femtosecond laser, the IntraLase® FS Laser.3 The laser is used to create a circular, hinged flap in the cornea, which allows the surgeon access to the tissue affecting the eye’s 1978 Radial Keratotomy is introduced by Svyatoslov Fyodorov shape.1 in the U.S. The procedure involves making a number of incisions in the cornea to change its shape and 2002 The STAR S4 IR® Laser is introduced. The X generation is correct refractive errors, such as myopia, hyperopia used in LASIK procedures today.4 and astigmatism.2,3 1970s Samuel Blum, Rangaswamy Srinivasan and James J. Wynne 2003 The FDA approves the use of wavefront technology,3 invent the excimer laser at the IBM Thomas J. Watson which creates a 3-D map of the eye to measure 1980s Research Center in Yorktown, New York.
    [Show full text]
  • Ocular Surface Changes Associated with Ophthalmic Surgery
    Journal of Clinical Medicine Review Ocular Surface Changes Associated with Ophthalmic Surgery Lina Mikalauskiene 1, Andrzej Grzybowski 2,3 and Reda Zemaitiene 1,* 1 Department of Ophthalmology, Medical Academy, Lithuanian University of Health Sciences, 44037 Kaunas, Lithuania; [email protected] 2 Department of Ophthalmology, University of Warmia and Mazury, 10719 Olsztyn, Poland; [email protected] 3 Institute for Research in Ophthalmology, Foundation for Ophthalmology Development, 61553 Poznan, Poland * Correspondence: [email protected] Abstract: Dry eye disease causes ocular discomfort and visual disturbances. Older adults are at a higher risk of developing dry eye disease as well as needing for ophthalmic surgery. Anterior segment surgery may induce or worsen existing dry eye symptoms usually for a short-term period. Despite good visual outcomes, ocular surface dysfunction can significantly affect quality of life and, therefore, lower a patient’s satisfaction with ophthalmic surgery. Preoperative dry eye disease, factors during surgery and postoperative treatment may all contribute to ocular surface dysfunction and its severity. We reviewed relevant articles from 2010 through to 2021 using keywords “cataract surgery”, ”phacoemulsification”, ”refractive surgery”, ”trabeculectomy”, ”vitrectomy” in combina- tion with ”ocular surface dysfunction”, “dry eye disease”, and analyzed studies on dry eye disease pathophysiology and the impact of anterior segment surgery on the ocular surface. Keywords: dry eye disease; ocular surface dysfunction; cataract surgery; phacoemulsification; refractive surgery; trabeculectomy; vitrectomy Citation: Mikalauskiene, L.; Grzybowski, A.; Zemaitiene, R. Ocular Surface Changes Associated with Ophthalmic Surgery. J. Clin. 1. Introduction Med. 2021, 10, 1642. https://doi.org/ 10.3390/jcm10081642 Dry eye disease (DED) is a common condition, which usually causes discomfort, but it can also be an origin of ocular pain and visual disturbances.
    [Show full text]
  • Refractive Surgery Faqs. Refractive Surgery the OD's Role in Refractive
    9/18/2013 Refractive Surgery Refractive Surgery FAQs. Help your doctor with refractive surgery patient education Corneal Intraocular Bill Tullo, OD, FAAO, LASIK Phakic IOL Verisys Diplomate Surface Ablation Vice-President of Visian PRK Clinical Services LASEK CLE – Clear Lens Extraction TLC Laser Eye Centers Epi-LASIK Cataract Surgery AK - Femto Toric IOL Multifocal IOL ICRS - Intacs Accommodative IOL Femtosecond Assisted Inlays Kamra The OD’s role in Refractive Surgery Refractive Error Determine the patient’s interest Myopia Make the patient aware of your ability to co-manage surgery Astigmatism Discuss advancements in the field Hyperopia Outline expectations Presbyopia/monovision Presbyopia Enhancements Risks Make a recommendation Manage post-op care and expectations Myopia Myopic Astigmatism FDA Approval Common Use FDA Approval Common Use LASIK: 1D – 14D LASIK: 1D – 8D LASIK: -0.25D – -6D LASIK: -0.25D – -3.50D PRK: 1D – 13D PRK: 1D – 6D PRK: -0.25D – -6D PRK: -0.25D – -3.50D Intacs: 1D- 3D Intacs: 1D- 3D Intacs NONE Intacs: NONE P-IOL: 3D- 20D P-IOL: 8D- 20D P-IOL: NONE P-IOL: NONE CLE/CAT: any CLE/CAT: any CLE/CAT: -0.75D - -3D CLE/CAT: -0.75D - -3D 1 9/18/2013 Hyperopia Hyperopic Astigmatism FDA Approval Common Use FDA Approval Common Use LASIK: 0.25D – 6D LASIK: 0.25D – 4D LASIK: 0.25D – 6D LASIK: 0.25D – 4D PRK: 0.25D – 6D PRK: 0.25D – 4D PRK: 0.25D – 6D PRK: 0.25D – 4D Intacs: NONE Intacs: NONE Intacs: NONE Intacs: NONE P-IOL: NONE P-IOL: NONE P-IOL: NONE P-IOL:
    [Show full text]
  • Laser Vision Correction Surgery
    Patient Information Laser Vision Correction 1 Contents What is Laser Vision Correction? 3 What are the benefits? 3 Who is suitable for laser vision correction? 4 What are the alternatives? 5 Vision correction surgery alternatives 5 Alternative laser procedures 5 Continuing in glasses or contact lenses 5 How is Laser Vision Correction performed? 6 LASIK 6 Surface laser treatments 6 SMILE 6 What are the risks? 7 Loss of vision 7 Additional surgery 7 Risks of contact lens wear 7 What are the side effects? 8 Vision 8 Eye comfort 8 Eye Appearance 8 Will laser vision correction affect my future eye health care? 8 How can I reduce the risk of problems? 9 How much does laser vision correction cost? 9 2 What is Laser Vision Correction? Modern surgical lasers are able to alter the curvature and focusing power of the front surface of the eye (the cornea) very accurately to correct short sight (myopia), long sight (hyperopia), and astigmatism. Three types of procedure are commonly used in If you are suitable for laser vision correction, your the UK: LASIK, surface laser treatments (PRK, surgeon will discuss which type of procedure is the LASEK, TransPRK) and SMILE. Risks and benefits are best option for you. similar, and all these procedures normally produce very good results in the right patients. Differences between these laser vision correction procedures are explained below. What are the benefits? For most patients, vision after laser correction is similar to vision in contact lenses before surgery, without the potential discomfort and limitations on activity. Glasses may still be required for some activities after Short sight and astigmatism normally stabilize in treatment, particularly for reading in older patients.
    [Show full text]
  • Presbyopia Treatment by Monocular Peripheral Presbylasik
    Presbyopia Treatment by Monocular Peripheral PresbyLASIK Robert Leonard Epstein, MD, MSEE; Mark Andrew Gurgos, COA ABSTRACT spheric corneal LASIK laser ablation to produce a relatively more highly curved central cornea and PURPOSE: To investigate monocular peripheral presby- a relatively fl at midperipheral cornea has been A 1 LASIK on the non-dominant eye with distance-directed termed “central presbyLASIK” by Alió et al, who reported monofocal refractive surgery on the dominant eye in their surgical results using a proprietary ablation profi le with treating presbyopia. 6-month follow-up. Another proprietary central presbyLASIK technique was described and patented by Ruiz2 and indepen- METHODS: One hundred three patients underwent dently tested by Jackson3 in Canada. treatment with a VISX S4 system and follow-up from 1.1 to 3.9 years (mean 27.4 months). Average patient Peripheral presbyLASIK with a relatively fl atter central age was 53.3 years. Preoperative refraction ranged cornea and more highly curved corneal midperiphery was from Ϫ9.75 to ϩ2.75 diopters (D). Non-dominant eyes described by Avalos4 (PARM technique), and a proprietary underwent peripheral presbyLASIK—an aspheric, pupil– peripheral presbyLASIK algorithm was described and patent- size dependent LASIK to induce central corneal relative ed by Tamayo.5 Telandro6 reported 3-month follow-up results fl attening and peripheral corneal relative steepening. Dominant eyes underwent monofocal refraction-based on a different peripheral presbyLASIK algorithm. 7 LASIK (75.8%), wavefront-guided LASIK, limbal relaxing McDonnell et al fi rst described improved visual acuity from incisions, or no treatment to optimize distance vision. a multifocal effect after radial keratotomy.
    [Show full text]
  • Refractive Errors a Closer Look
    2011-2012 refractive errors a closer look WHAT ARE REFRACTIVE ERRORS? WHAT ARE THE DIFFERENT TYPES OF REFRACTIVE ERRORS? In order for our eyes to be able to see, light rays must be bent or refracted by the cornea and the lens MYOPIA (NEARSIGHTEDNESS) so they can focus on the retina, the layer of light- sensitive cells lining the back of the eye. A myopic eye is longer than normal or has a cornea that is too steep. As a result, light rays focus in front of The retina receives the picture formed by these light the retina instead of on it. Close objects look clear but rays and sends the image to the brain through the distant objects appear blurred. optic nerve. Myopia is inherited and is often discovered in children A refractive error means that due to its shape, your when they are between ages eight and 12 years old. eye doesn’t refract the light properly, so the image you During the teenage years, when the body grows see is blurred. Although refractive errors are called rapidly, myopia may become worse. Between the eye disorders, they are not diseases. ages of 20 and 40, there is usually little change. If the myopia is mild, it is called low myopia. Severe myopia is known as high myopia. Lens Retina Cornea Lens Retina Cornea Light rays Light is focused onto the retina Light rays Light is focused In a normal eye, the cornea and lens focus light rays on in front of the retina the retina. In myopia, the eye is too long or the cornea is too steep.
    [Show full text]
  • Facts You Need to Know About Laser Assisted in Situ Keratomileusis (LASIK) and Photorefractive Keratectomy (PRK) Surgery
    Facts You Need to Know About Laser Assisted In Situ Keratomileusis (LASIK) and Photorefractive Keratectomy (PRK) Surgery Patient Information Booklet LASIK: Nearsighted Patients (0 to -14.0 diopters) with or without -0.5 to -5.0 Diopters of Astigmatism Farsighted Patients (+0.5 to +5.0 diopters) with up to +3.0 Diopters of Refractive Astigmatism Mixed Astigmatism Patients (≤ 6.0 diopters of astigmatism) PRK: Nearsighted Patients (-1.0 to -12.0 diopters) or Nearsighted Patients (0 to -12.0 diopters) with up to -4.0 Diopters of Astigmatism Farsighted Patients (+1.0 to +6.0 diopters) with no more than 1.0 Diopter of Refractive Astigmatism Farsighted Patients (+0.5 to +5.0 diopters) with +0.5 to +4.0 Diopters of Refractive Astigmatism Please read this entire booklet. Discuss its contents with your doctor so that all your questions are answered to your satisfaction. Ask any questions you may have before you agree to the surgery. VISX, Incorporated 3400 Central Expressway Santa Clara, CA 95051-0703 U.S.A. Tel: 408.733.2020 Copyright 2001 by VISX, Incorporated All Rights Reserved VISX® is a registered trademark of VISX, Incorporated. VISX STAR Excimer Laser System™ is a trademark of VISX, Incorporated. Accutane® is a registered trademark of Hoffmann-La Roche Inc. Cordarone® is a registered trademark of Sanofi. Imitrex® is a registered trademark of Glaxo Group Ltd. Table of Contents Introduction . 1 How the Eye Functions . 2 What are PRK and LASIK? . 5 Benefits . 6 Risks . 6 The First Week Following Surgery . 7 The First Two To Six Months Following Surgery .
    [Show full text]
  • Refractive Surgery Reference Guide
    REFRACTIVE SURGERY REFERENCE GUIDE Laser Vision Clinic Central Coast Suite 1 Fountain Corporate 2 Ilya Avenue ERINA NSW 2250 Phone: (02) 4367 0055 Fax: (02) 4367 3881 Email: [email protected] 1 Table of Contents REFRACTIVE SURGERY ...................................................................................................................................1 REFERENCE GUIDE .........................................................................................................................................1 1. Brief History of Refractive Surgery ........................................................................................................5 2. Overview of the main refractive surgery techniques used at LVCCC ....................................................6 3. The Laser Vision Clinic Central Coast .....................................................................................................7 4. Referral Procedure for Patients Coming to LVCCC ................................................................................8 5. Assessment of Patients at LVCCC ..........................................................................................................9 6. Patient Education ............................................................................................................................... 10 7. LASIK ................................................................................................................................................... 11 7.1. The Main Suitability Criteria: .....................................................................................................
    [Show full text]
  • Laser Vision Correction: a Tutorial for Medical Students
    Laser Vision Correction: A Tutorial for Medical Students Written by: Reid Turner, M4 Reviewed by: Anna Kitzmann, MD Illustrations by: Steve McGaughey, M4 November 29, 2011 1. Introduction Laser vision correction is the world’s most popular elective surgery with roughly 700,000 LASIK procedures performed in the U.S. each year (AAO, 2008). Since refractive errors affect half of the U.S. population 20 years of age and older, it comes as no surprise that many people are turning to laser vision correction to obtain improved vision (Vitale et al. 2008). Due to its popularity, medical students will inevitably be asked by patients, family, and friends about refractive eye surgery. It is important to have a basic understanding of laser vision correction, outcomes, and associated risks. The goal of laser vision correction is to decrease dependence on glasses and contact lenses by focusing light more effectively on the retina. While there are a number of different surgeries used to achieve this result, this tutorial will focus specifically on laser vision correction, which consists of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). In the U.S., LASIK comprises about 85% of the laser vision correction market with PRK making up the other 15% (ISRS 2009). The cost of surgery varies in price from hundreds to thousands of dollars and is not covered by insurance, similar to cosmetic surgery. Laser vision correction is regarded as highly effective with studies showing 94% of patients achieving uncorrected visual acuity of 20/40 or better at 12 months (Salz et al. 2002), which is the visual acuity needed to drive without corrective lenses in most states.
    [Show full text]
  • Dry Eye Disease Management for IMPROVING PATIENT OUTCOMES
    CME MONOGRAPH Visit https://tinyurl.com/DEDOutcomesCME for online testing and instant CME certificate. CURRENT PERSPECTIVES Dry Eye Disease Management FOR IMPROVING PATIENT OUTCOMES FACULTY TERRY KIM, MD (CHAIR) • ROSA BRAGA-MELE, MD, MEd, FRCSC JESSICA CIRALSKY, MD • CHRISTOPHER J. RAPUANO, MD Original Release: May 1, 2019 • Expiration: May 31, 2020 This continuing medical education activity is jointly provided by New York Eye and Ear Infirmary of Mount Sinai and MedEdicus LLC. This continuing medical education activity is supported through an unrestricted educational grant from Shire. Distributed with LEARNING METHOD AND MEDIUM Jessica Ciralsky, MD, had a financial agreement or affiliation during the This educational activity consists of a supplement and ten (10) study past year with the following commercial interests in the form of Consultant/ questions. The participant should, in order, read the learning objectives Advisory Board: Allergan; and Shire. contained at the beginning of this supplement, read the supplement, Terry Kim, MD, had a financial agreement or affiliation during the past answer all questions in the post test, and complete the Activity year with the following commercial interests in the form of Consultant/ Evaluation/Credit Request form. To receive credit for this activity, Advisory Board: Actavis; Aerie Pharmaceuticals, Inc; Alcon; Allergan; please follow the instructions provided on the post test and Activity Avedro, Inc; Avellino Labs; Bausch & Lomb Incorporated; BlephEx; Evaluation/Credit Request form. This educational
    [Show full text]
  • Refractive Surgery Speaker Notes
    Eye Care Skills: Presentations for Physicians and Other Health Care Professionals Version 3.0 Refractive Surgery Speaker Notes Karla J. Johns, MD Executive Editor Copyright © 2009 American Academy of Ophthalmology. All rights reserved. Developed by The Academy gratefully acknowledges the Michael Conners, MD, PhD, contributions of numerous past reviewers and and Kenneth Maverick, MD, advisory committee members who have in conjunction with the Ophthalmology Liaisons played a role in the development of previous Committee of the American Academy of editions of the Eye Care Skills slide-script. Ophthalmology Academy Staff Reviewer, 2009 Revision Richard A. Zorab Carla J. Siegfried, MD Vice President, Ophthalmic Knowledge Barbara Solomon Executive Editor, 2009 Revision Director of CME, Programs & Acquisitions Karla J. Johns, MD Susan R. Keller Ophthalmology Liaisons Committee Program Manager, Ophthalmology Liaisons Carla J. Siegfried, MD, Chair Laura A. Ryan Donna M. Applegate, COT Editor James W. Gigantelli, MD, FACS Debra Marchi Kate Goldblum, RN Permissions Karla J. Johns, MD Miriam T. Light, MD Mary A. O'Hara, MD Judy Petrunak, CO, COT David Sarraf, MD Samuel P. Solish, MD Kerry D. Solomon, MD The authors state that they have no significant financial or other relationship Slides 4, 6, 7, 8, 25, 31, 36, and 38 are reprinted from Advances in Refractive with the manufacturer of any commercial product or provider of any Surgery PowerPoint presentations with permission of the American Academy commercial service discussed in the material they contributed to this of Ophthalmology, copyright © 2005. All rights reserved. publication or with the manufacturer or provider of any competing product or service. Slides 10 and 12 are reprinted, with permission, from Bradford CA, Basic Ophthalmology for Medical Students and Primary Care Residents, 8th The American Academy of Ophthalmology provides this material for Edition, San Francisco: American Academy of Ophthalmology; 2004.
    [Show full text]
  • Refractive Surgery
    Corporate Medical Policy Refractive Surgery File Name: refra ctive_surgery Origination: 4/1981 Last CAP Review: 6/2021 Next CAP Review: 6/2022 Last Review: 6/2021 Description of Procedure or Service The term refractive surgery describes various procedures that modify the refractive error of the eye. Refractive surgery involves surgery performed to reshape the cornea of the eye (refractive keratoplasty) or the way the eye focuses light internally. Vision occurs when light rays are bent or refracted by the cornea a nd lens and received by the retina, (the nerve layer at the back of the eye), in the form of an image, which is sent through the optic nerve to the brain. Refractive errors occur when the eye cannot properly focus light and images a ppear out of focus. The main types of refractive errors a re myopia (nearsightedness), hyperopia (farsightedness) and astigmatism (distortion). Presbyopia (aging eye) is a problem of the lens and is characterized by the inability to bring close objects into focus. Refractive errors are generally corrected with glasses or contact lenses. Refractive keratoplasty includes all surgical procedures on the cornea to improve vision by changing the shape, and thus the refractive index, of the corneal surface. Refractive keratoplasties can be broadly subdivided into keratotomies, i.e., corneal incisions; keratectomies, i.e., removal of corneal epithelium; a nd keratomileusis, i.e., resha ping a stromal layer of the cornea. Refractive keratoplasties include the following surgeries: Ra dial keratotomy (RK) is a surgica l procedure for nearsightedness. Using a high-powered microscope, the physician places micro-incisions (usually 8 or fewer) on the surface of the cornea in a pattern much like the spokes of a wheel.
    [Show full text]