Handbook of Visual Optics, Volume One by Pablo Artal

885bb80cda1acc0-261x361.jpg Author Pablo Artal
Isbn 9781482237856
File size 24MB
Year 2017
Pages 449
Language English
File format PDF
Category biology


HANDBOOK OF VISUAL OPTICS VOLUME I Handbook of Visual Optics Handbook of Visual Optics: Fundamentals and Eye Optics, Volume One Handbook of Visual Optics: Instrumentation and Vision Correction, Volume Two HANDBOOK OF VISUAL OPTICS Fundamentals and Eye Optics edited by Pablo Artal VOLUME I MATL AB® is a trademark of The MathWorks, Inc. and is used with permission. The MathWorks does not warrant the accuracy of the text or exercises in this book. This book’s use or discussion of MATLAB® software or related products does not constitute endorsement or sponsorship by The MathWorks of a particular pedagogical approach or particular use of the MATLAB® software. CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2017 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed on acid-free paper Version Date: 20161115 International Standard Book Number-13: 978-1-4822-3785-6 (Hardback) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. 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Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging‑in‑Publication Data Names: Artal, Pablo, editor. Title: Handbook of visual optics / [edited by] Pablo Artal. Description: Boca Raton : Taylor & Francis, [2017] | Includes bibliographical references. Identifiers: LCCN 2016030030| ISBN 9781482237856 (hbk : alk. paper) | ISBN 9781315373034 (ebk) | ISBN 9781315355726 (epub) | ISBN 9781315336664 (mobi/Kindle) | ISBN 9781482237863 (web PDF) Subjects: | MESH: Vision, Ocular--physiology | Optical Phenomena | Vision Tests--instrumentation | Eye Diseases--therapy Classification: LCC QP475 | NLM WW 103 | DDC 612.8/4--dc23 LC record available at https://lccn.loc.gov/2016030030 Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com Contents Preface Editor Contributors Part I INtrODUCtION 1. History of physiological optics in the twentieth century Gerald Westheimer 2. Possibilities in physiological optics David R. Williams and Sarah Walters Part II FUNDaMENtaLS vii ix xi 1 3 11 25 3. Geometrical optics Jim Schwiegerling 27 4. Wave optics Daniel Malacara 39 5. aberrations in optical systems José Sasián 75 6. Photometry Yoshi Ohno 83 7. Characterization of visual stimuli using the standard display model Joyce E. Farrell, Haomiao Jiang, and Brian A. Wandell 93 8. Basic ophthalmic instruments Walter D. Furlan 103 9. Instrumentation for adaptive optics Chris Dainty 121 10. anatomy and embryology of the eye: an overview Vivian Choh and Jacob G. Sivak 129 11. the retina Michael A. Freed 141 12. Visual system architecture Jonathan Winawer and Hiroshi Horiguchi 159 13. Visual psychophysical methods Denis G. Pelli and Joshua A. Solomon 181 Part III OPtICaL PrOPErtIES OF tHE EYE 187 14. the cornea Michael Collins, Stephen Vincent, and Scott Read 189 15. the lens Fabrice Manns, Arthur Ho, and Jean-Marie Parel 211 16. Schematic eyes David A. Atchison 235 17. axes and angles of the eye David A. Atchison 249 18. the retina and the Stiles– Crawford effects Brian Vohnsen 257 vi Contents 19. refractive errors David A. Wilson 277 20. Monochromatic aberrations Susana Marcos, Pablo Pérez-Merino, and Carlos Dorronsoro 293 21. Peripheral aberrations Linda Lundström and Robert Rosén 313 22. Customized eye models Juan Tabernero 337 23. Scattering, straylight, and glare Thomas J.T.P. van den Berg 349 24. accommodation mechanisms Shrikant R. Bharadwaj 363 25. accommodation dynamics Lyle S. Gray and Barry Winn 377 26. Eye Movements Andrew J. Anderson 387 27. aging and the eye’s optics W. Neil Charman 405 28. Polarization properties Juan M. Bueno 413 Index 431 Preface For many years, first as a student and later as a senior researcher in the area of physiological optics, I have wanted a comprehensive resource for frequently arising questions. Although the situation in today’s Internet era is different than before, still I believe there is need for a reliable single source of encyclopedic knowledge. Finally, the dream of my youth—a handbook in visual optics—is a reality and in your hands (or on your screen). I hope this will help interested readers for a long time to come. At the beginning of this adventure of compiling the handbook, I wanted to accomplish a number of goals (probably, too many!). Among others, I wanted to provide general useful information for beginners, or for those approaching the field from other disciplines, and the latest research presented from the most recent experiments in laboratories. As with most activities in life, success depends on the quality of individuals involved. In this regard, I was tremendously fortunate to have such an exceptional group of contributors. If we can apply the optical equivalence, this handbook is the result of a coherent superposition of exceptional expertise. This handbook builds from the fundamentals to the current state of the art of the field of visual optics. The eye as an optical instrument plays a limiting role in the quality of our vision. A better understanding of the optics of the eye is required both for ophthalmic instrumentation and vision correction. The handbook covers the physics and engineering of instruments together with procedures to correct the ocular optics and its impact on visual perception. The field of physiological, or visual, optics is a classic area in science, an arena where many new practical technologies have been tested and perfected. Many of the most brilliant scientists in history were interested in the eye. Based in well-established physical and physiological principles, the area was described as nearly completed in the second part of the twentieth century. However, from the 1980s onward, a tremendous new interest in this field appeared. This was driven in part by new technology, such as lasers and electronic cameras, which allowed the introduction of new instrumentation. For example, the use of wave-front sensors and adaptive optics concepts on the eye completely changed the field. In relatively few years, these ideas expanded to the clinical areas of ophthalmology and optometry. Today, research in new aspects of vision correction and instruments is extremely active, with many groups working on it around the world. This area is a mixture of fundamentals and applications, and is at the crossroad of many disciplines: physics, medicine, biology, psychology, and engineering. I tried to find an equilibrium among the different approaches and sensibilities to serve all tastes. This book can be accessed sequentially, but also by individual parts whenever a particular topic is required. The handbook is organized in two volumes, with five total parts. Volume One begins with an introductory part that gives an exceptional appetizer by two giants of the field: Gerald Westheimer presents an historical account of the field, and David Williams explores the near past and the future. Part II covers background and fundamental information on optical principles, ocular anatomy and physiology, and the eye and ophthalmic instruments. Each chapter is self-contained but oriented to provide the proper background for the rest of the handbook. Basic optics is covered by Schwiegerling (geometrical optics), Malacara (wave optics), and Sasián (aberrations). The concepts of photometry and colorimetry are summarized in Chapter 6 (Ohno). The basics and limits of the generation of visual stimuli are described in Chapter 7 (Farrell et al.). Furlan provides a complete revision on the main ophthalmic instruments, and Dainty an introduction on adaptive optics. While the first chapters of this part are devoted to the more technical aspects, the three next chapters have a different orientation to provide the physiological basis for the eye and the visual system. Choh and Sivak describe the anatomy and embryology of the eye in Chapter 10. Freed reviews the retina, and Winawer the architecture of the visual system. In the final chapter in this part, Pelli and Solomon describe psychophysical methods. Part II sets the foundation for the various principles that follow in the rest of the handbook. Part III covers the current state of the art on the understanding of the optics of the eye and the retina. Collins et al. and Manns describe, respectively, what we know today about the optical properties of the cornea and the lens. Atchison reviews in Chapters 16 and 17 the different schematics eyes and the definitions and implications of the axes and angles in ocular optics. The optics of the retina is detailed in Chapter 18 (Vohnsen). Once the different components are evaluated, the next chapters concentrate on the impact of optical quality. Refractive errors (Wilson) and monochromatic (Marcos et al.) aberrations are described. Although traditionally most attention has been paid to optical characteristics of the eye in the fovea, the important role of peripheral optics is described in Chapter 21 (Lundström and Rosén). Tabernero describes personalized eye models in Chapter 22. Beyond refractive errors and aberrations, scattering in the eye affects image quality. van den Berg exhaustively reviews the state of the art of the impact and measurements of this phenomenon (Chapter 23). The eye in young subjects has the ability to focus objects placed at different distances efficiently. Bharadwaj provides a review of the accommodative mechanism (Chapter 24), and Winn and Gray describe its dynamics (Chapter 25). The eyes are continually moving to place the fovea on the area of interest. This dynamic behavior has important implications described in Chapter 26 (Anderson). Although the human eye is very robust, serving us over many years, aging obviously affects its optics. In Chapter 27, Charman reviews how the eye changes with age. Several species are able to detect the state of polarization of light. Although our visual system is not capable of something similar, polarization plays a role in optical properties as described in Chapter 28 (Bueno). Volume Two focuses on the important topics of instrumentation and vision correction. Part I is dedicated to novel ophthalmic instrumentation for imaging, including the anterior segment and the retina, and for visual testing. An introductory chapter is dedicated to reviewing the concepts of light safety (Barat). Molebny presents a complete description of different wavefront sensors and aberrometers in Chapter 2. Hitzenberger reviews the principle viii Preface of low-coherence interferometry (Chapter 3). This was the basis for one of the most successful techniques in ophthalmology: optical coherence tomography (OCT). Grulkowski concentrates on the current state of the art in OCT applied to the anterior segment (Chapter 4). Popovic (Chapter 5) and Doble (Chapter 6) present how adaptive optics implemented in ophthalmoscopes has changed the field in recent years. A different application of adaptive optics is its use for visual testing. Fernandez (Chapter 7) shows the history, present, and future potential of this technology. Imaging of the ocular media using multiphoton microscopy is a recent scientific frontier. Jester (Chapter 8) and Hunter (Chapter 9) cover, respectively, the applications of this emerging technology for the cornea and the retina. Part II describes the different devices and techniques for surgical and nonsurgical visual correction procedures, from traditional to futuristic approaches. Ophthalmic lenses are still the most widely used approach and clearly deserve to be well recognized. Malacara (Chapter 10) presents a complete overview of this topic. Contact lenses are described in depth in Chapter 11 (Cox). The specific case of correcting highly aberrated eyes is addressed in Chapter 12 (Marsack and Applegate). A particularly relevant type of correcting devices is intraocular lenses (IOLs), implanted to substitute the crystalline lens after cataract surgery. Two emerging types of IOLs, accommodating and adjustable, are reported in Chapters 13 (Findl and Himschall) and 14 (Sandstedt). Chapter 15 (Alio and El Bahrawy) presents a review of refractive surgical approaches for the cornea. The potential for nonlinear manipulation of the ocular tissues may open the door to new reversible future treatments. Chapter 17 (van de Pol) presents the state of the art of using corneal onlays and inlays for vision correction. Part III reviews the relationship between the ocular optics and visual perception. Aspects related to optical visual metrics (Chapter 18, Guirao) and the prediction of visual acuity (Chapter 19, Navarro) are included. Adaptation is a key element in vision and may have significant clinical implications. Chapters 20 (Webster and Marcos) and 21 (Shaeffel) describe adaptation to blur and contrast. Visual functions change with age. A description of these characteristics is a useful resource for those interested in any practical application. Chapter 22 (Wood) reviews age-related aspects of vision. Finally, Chapter 23 (Jimenez) explores the impact of the eye’s optics in stereovision. I thank the many people who contributed to this handbook: of course, all the authors for providing accurate and up-to-date chapters; Carmen Martinez for helping me with secretarial work, and Luna Han from Taylor & Francis Group for her guidance and patience. I am also indebted to the financial help received by my lab, which allowed dedication to this endeavor: the European Research Council, the Spanish Ministry of Science, and the Fundacion Seneca, Murcia region, Spain. Pablo Artal Universidad de Murcia Murcia, Spain Editor Pablo Artal was born in Zaragoza (Spain) in 1961. He studied Physics at the University of Zaragoza. In 1984, he moved to Madrid with a predoctoral fellowship to work at the CSIC “Instituto de Optica.” He was a postdoctoral research fellow, first at Cambridge University (UK) and later at the Institut d’Optique in Orsay, France. After his return to Spain, he obtained a permanent researcher position at the CSIC in Madrid. In 1994 he became the first full professor of optics at the University of Murcia, Spain, where he founded his “Laboratorio de Optica.” Prof. Artal was secretary of the Spanish Optical Society from 1990 to 1994, associated dean of the University of Murcia Science Faculty from 1994 to 2000, and director of the Physics Department at Murcia University from 2001 to 2003. From 2004 to 2007 he was in charge of the reviewing grants panel in physics at the Spanish Ministry of Science in Madrid. Since 2006 he is the founding director of the Center for Research in Optics and Nanophysics at Murcia University. He was president of the Academy of Science of the Murcia Region from 2010 to 2015. From 2015 he is the president of the “Fundación de Estudios Medicos,” an outreach organization dedicated to promote science. During his career he often spent periods doing collaborative research in laboratories in Europe, Australia, Latin America, and the United States. This included two sabbatical years in Rochester (USA) and Sydney (Australia). Dr. Artal’s research interests are centered on the optics of the eye and the retina and the development of optical and electronic imaging techniques to be applied in vision, ophthalmology, and biomedicine. He has pioneered a number of highly innovative and significant advances in the methods for studying the optics of the eye and has contributed substantially to our understanding of the factors that limit human visual resolution. In addition, several of his results and ideas in the area of ophthalmic instrumentation over the last years have been introduced in instruments and devices currently in use in clinical ophthalmology. He has published more than 200 reviewed papers that received more than 7600 citations with an H-index of 45 (12700 and 60 in Google scholar) and presented more than 200 invited talks in international meetings and around 150 seminars in research institutions around the world. He was elected fellow member of the Optical Society of America (OSA) in 1999, fellow of the Association for Research in Vision and Ophthalmology in 2009 and 2013 (gold class), and fellow of the European Optical Society in 2014. In 2013, he received the prestigious award “Edwin H. Land Medal” for his scientific contributions to the advancement of diagnostic and correction alternatives in visual optics. This award was established by the OSA and the Society for Imaging Science and Technology to honor Edwin H. Land. This medal recognizes pioneering work empowered by scientific research to create inventions, technologies, and products. In 2014, he was awarded with a prestigious “Advanced Grant” of the European Research Council. In 2015, he received the “King Jaime I Award on New Technologies” (applied research). This is one of the most prestigious awards for researchers in all areas in Spain. It consists of a medal, mention, and 100000€ cash prize. He is a coinventor of 22 international patents in the field of optics and ophthalmology. Twelve of them extended to different countries and in some cases expanded to complete families of patents covering the world. Several of his proposed solutions and instruments are currently in use in the clinical practice. Dr. Artal is the cofounder of three spin-off companies developing his concepts and ideas. He has been the mentor of many graduate and postdoctoral students. His personal science blog is followed by readers, mostly graduate students and fellow researchers, from around the world. He has been editor of the Journal of the Optical Society of America A and the Journal of Vision. Contributors Andrew J. Anderson Department of Optometry and Vision Sciences The University of Melbourne Melbourne, Victoria, Australia Michael A. Freed Department of Neuroscience University of Pennsylvania Philadelphia, Pennsylvania David A. Atchison School of Optometry and Vision Science Queensland University of Technology Brisbane, Queensland, Australia Walter D. Furlan Diffractive Optics Group Universidad de Valencia Valencia, Spain Shrikant R. Bharadwaj Brien Holden Institute of Optometry and Vision Sciences Bausch and Lomb School of Optometry and Hyderabad Eye Research Foundation L V Prasad Eye Institute Hyderabad, India Lyle S. Gray Department of Life Sciences Glasgow Caledonian University Glasgow, United Kingdom Juan M. Bueno Laboratorio de Óptica Universidad de Murcia Murcia, Spain W. Neil Charman Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health University of Manchester Manchester, United Kingdom Arthur Ho Brien Holden Vision Institute Sydney, Australia and Miller School of Medicine University of Miami Miami, Florida and School of Optometry and Vision Science University of New South Wales Sydney, Australia Vivian Choh School of Optometry and Vision Science University of Waterloo Waterloo, Ontario, Canada Hiroshi Horiguchi Department of Ophthalmology Jikei University School of Medicine Tokyo, Japan Michael Collins School of Optometry and Vision Science Queensland University of Technology Brisbane, Queensland, Australia Haomiao Jiang Department of Psychology Stanford University Stanford, California Chris Dainty Institute of Ophthalmology University College London London, United Kingdom Carlos Dorronsoro Instituto de Optica Consejo Superior de Investigaciones Científicas Madrid, Spain Joyce E. Farrell Department of Electrical Engineering Stanford University Stanford, California Linda Lundström Department of Applied Physics KTH Royal Institute of Technology Stockholm, Sweden Daniel Malacara Centro de Investigación en Optica León, Mexico Fabrice Manns College of Engineering and Bascom Palmer Eye Institute University of Miami Coral Gables, Florida xii Contributors Susana Marcos Instituto de Optica Consejo Superior de Investigaciones Científicas Madrid, Spain Juan Tabernero Laboratorio de Óptica Universidad de Murcia Murcia, Spain Yoshi Ohno Sensor Science Division National Institute of Standards and Technology Gaithersburg, Maryland Thomas J.T.P. van den Berg Netherlands Institute for Neuroscience Royal Academy Amsterdam, the Netherlands Jean-Marie Parel Bascom Palmer Eye Institute and College of Engineering University of Miami Miami, Florida Stephen Vincent School of Optometry and Vision Science Queensland University of Technology Brisbane, Queensland, Australia Denis G. Pelli Department of Psychology Center for Neural Science New York University New York, New York Pablo Pérez-Merino Instituto de Optica Consejo Superior de Investigaciones Científicas Madrid, Spain Scott Read School of Optometry and Vision Science Queensland University of Technology Brisbane, Queensland, Australia Robert Rosén Applied Research AMO Groningen BV Groningen, the Netherlands José Sasián College of Optical Sciences University of Arizona Tucson, Arizona Jim Schwiegerling College of Optical Sciences University of Arizona Tucson, Arizona Jacob G. Sivak School of Optometry and Vision Science University of Waterloo Waterloo, Ontario, Canada Joshua A. Solomon Centre for Applied Vision Research City University London London, United Kingdom Brian Vohnsen School of Physics University College Dublin Dublin, Ireland Sarah Walters Center for Visual Science University of Rochester Rochester, New York Brian A. Wandell Department of Electrical Engineering and Psychology Department Stanford University Stanford, California Gerald Westheimer Department of Molecular and Cell Biology University of California, Berkeley Berkeley, California David R. Williams Center for Visual Science University of Rochester Rochester, New York David A. Wilson Brien Holden Vision Institute and School of Optometry and Vision Science University of New South Wales Sydney, New South Wales, Australia Jonathan Winawer Department of Psychology Center for Neural Science New York University New York, New York Barry Winn Sohar University Sohar, Sultanate of Oman Part Introduction I 1 History of physiological optics in the twentieth century Gerald Westheimer Contents 1.1 1.2 1.3 Status at the beginning of the century The foundations Structural optics of the eye 1.3.1 Eye dimension and axial length 1.3.2 Cornea 1.3.3 The crystalline lens 1.3.4 Transmission of the ocular media 1.3.5 Retinal optics 1.4 The retinal image 1.4.1 Aberrations of the eye 1.4.2 Quality of the retinal image 1.4.3 Optical transfer function 1.4.4 Strehl ratio 1.4.5 Stray light 1.5 Ophthalmic instrumentation 1.5.1 Ophthalmoscopy 1.5.2 Optometers and automatic objective refractometers 1.6 Spurt at the end of the twentieth century References 1.1 STATUS AT THE BEGINNING OF THE CENTURY Physiological Optics, as confirmed by its central manifestation, Helmholtz’s three-volume handbook, was understood at the time to be synonymous with the current Vision Science. But nomenclature has to go along with the explosive expansion of scientific knowledge. Hence the more optical components are now subsumed under Visual Optics, and even here further subdivision is needed. Optical imagery in the living eye is continually conditioned on factors arising from being embedded in motor apparatuses, specifically those controlling the pupil aperture and the ciliary muscle. Hence a division into structural visual optics, relating to the image-forming properties of the static normal eye, and functional visual optics, which would fold in accommodative and aperture size factors, seems indicated. Though it is not recognized as a distinct discipline, one can identify a branch of research as histological optics. Insofar as it transmits light unimpeded, eye tissue, such as the cornea and the crystalline lens, needs to have unusual biological structure. This became more evident and constituted a challenge around the middle of the century when electron microscopy began to reveal the subcellular makeup of corneal and lenticular layers. 3 3 4 4 4 4 5 5 5 5 5 6 6 6 7 7 7 7 8 The pioneering study by David Maurice (1957) on the cornea was influential here. The final biological stage of light capture resides in the receptors. Starting with an observation by Ernst Brücke in the 1840s, there have been consistent attempts to assign to them special light-gathering properties. The directional sensitivity and wave guide nature of retinal receptors has been an active area now for the last 80 years. It may be noted parenthetically that the optics of invertebrate eyes, left out of consideration in this review, has deservedly been given much attention (Exner 1891, Snyder and Menzel 1975, Land and Nilsson 2002). 1.2 THE FOUNDATIONS The eye’s image-forming properties were well understood in the middle of the eighteenth century as shown in the classic treatise by Robert Smith (1689–1768) (Smith 1738). Through the efforts of astronomers, for example, Bessel, Seidel, and Airy (1801–1892), optics as a discipline was thoroughly established in the nineteenth century. Maxwell’s (1831–1879) electromagnetic theory took command of the subject in 1861 and has never needed superseding. The giants of physiological optics, Thomas Young (1773–1839), Jan Purkinje (1787–1869), Listing (1808–1882), and Introduction 4 History of physiological optics in the twentieth century Helmholtz (1821–1894), laid and cemented the foundations, and ophthalmologists Donders (1818–1889), Landolt (1846–1926), and Snellen (1834–1908) developed clinical applications. Thus, a century ago, at the time of the beginning of the First World War, a student had available comprehensive compendia containing the available knowledge, specifically Helmholtz’s Physiological Optics in the new edition updated in particular by Gullstrand (1862–1930), the Graefe-Saemisch Handbuch der Augenheilkunde in its many volumes and several editions, followed in the next couple of decades by important chapters in Vol XII of Bethe et al., Handbuch der normalen und pathologischen Physiologie (1932) and in Abderhalden’s Handbuch (1920), and in Vol 1 of Duke-Elder’s Textbook of Ophthalmology (1932). When the author entered optometry school in 1940, the assigned textbook, the second edition of Emsley’s Visual Optics (Emsley 1939), contained a treatment of the subject that would rival current accounts and in some respects exceed their scope. By that time, too, quantum theory insofar as its characterization of the photon was concerned had solid footing and quite soon thereafter gripped the vision community when used to underpin our understanding of the absolute visual threshold (Hecht et al. 1942). The vision community has been well served by the authoritative treatment of the subject by Yves LeGrand (1908–1986) in various versions of his textbook (LeGrand 1949), a model of clarity. Exhaustive literature surveys of vision science up to the beginning of the twentieth century had been provided in the encyclopedic scholarship displayed in the appendixes by A. Koenig to the second edition of Helmholtz’s Physiological Optics (almost 8000 references up to 1894) and F. Hofmann in his Graefe-Saemisch Handbuch chapters (almost 1500 references on spatial vision alone) and by A. Tschermak in the voluminous footnotes of his chapters in Bethe et al. Handbuch (Tschermak 1931). As will be seen, developments in visual optics during the second half of the twentieth century required an expanded view beyond geometrical optics and the simple application of diffraction theory in Airy’s disk, yet the foundations for it were well in place. Abbe (1873) and Rayleigh (1896) in their treatment of microscope resolution used a framework that contained, almost explicitly, all the elements that were to become mainstream in the Fourier theory of optics that has since become dominant. Though it was more of academic than practical interest at the time, the theory applicable to coherent light (and what is more challenging, partially coherent light) was put on the table by van Cittert (1934), and so were the celebrated polynomials of Zernike (1934). The upswing in the growth of optics, specifically as it plays a role in vision, in the middle of the twentieth century thus had their origin elsewhere. Most prominently, it was the harnessing of scientific and industrial resources in the conduct of the Second World War that ended in 1945. The scientific community virtually unanimously rallied behind the war effort, contributing insight and inventiveness to a heady mixture that also included technological innovation and industrial prowess. After the war, this continued in university and some corporate laboratories, blossoming into a research enterprise of unprecedented magnitude and productivity. The sequence into cybernetics (Wiener 1948), information theory (Shannon and Weaver 1949), and the linear systems approach (Trimmer 1950) and control theory was seamless and so was the progress toward labs equipped with oscilloscopes, photomultipliers, digital computers, transistor devices, in time followed by lasers, LCD, and deformable mirrors. For decades, vision laboratories thrived on “war surplus” lenses, mirrors, prisms, and filters. Light that was once generated by candles, and had its intensity controlled by the inverse square law and its duration by episcotister disks, was produced by lamps with specific filaments and then by high-pressure mercury arcs with wavelength range restricted by narrowband interference filters and intensity adjusted by neutral density wedges. To achieve high retinal illuminance, the filaments were imaged in the pupil in Maxwellian view well before its optical subtleties had been realized (Westheimer 1966). 1.3 STRUCTURAL OPTICS OF THE EYE 1.3.1 EYE DIMENSION AND AXIAL LENGTH The ingenious method of measuring the eye’s axial length by utilizing x-ray phosphenes (Goldmann and Hagen 1942) soon gave way to sonography that in the form of corneal pachometry (Molinari 1982) is in clinical use and now has become a reliable means of evaluating the refractive needs associated with cataract extraction (Hoffer 1981). 1.3.2 CORNEA Because it is the principal source of the eye’s refractive power and because, unlike the other refractive surfaces, it is immediately accessible, the cornea has always attracted much attention. Gullstrand in his appendix to the Third Edition of Helmholtz went into much detail about the shape of the corneal surface and the various means of measuring it. Keratoscopy and keratometry formed a strong chapter in Abderhalden’s Handbuch. As contact lenses became ubiquitous and their fitting needed good information of the corneal surface on which they rested and whose optical properties they largely preempted, rapid and accurate measurements of corneal curvature could be performed in the clinic by cleverly designed electro-optical apparatuses, the subject of continued attention and technical innovation (Fowler and Dave 1994). Polarization effects, which can be made visible, have been ascribed to the cornea (Stanworth and Naylor 1950). 1.3.3 THE CRYSTALLINE LENS The anterior and posterior surfaces of the crystalline lens are of critical relevance in how the eye accommodates, that is, changes focus under neural control by contraction of the ciliary muscle. E.F. Fincham (1937a), in part using optical means, made the major contribution to this topic in his monograph. It became clear early in the optical modeling of the eye that the anterior and posterior curvature of the lens could not fully account for its total refractive power for a biologically realistic refractive index, and giving the eye a solid interior core was not supported by evidence. Hence the proposition that a remarkable proportion of its total refractive power is provided by a refractive index gradient had gained acceptance by the time Gullstrand wrote his 1911 appendix. More recent approaches show just how challenging a topic this is (Campbell 1984, Pierscionek and Chan 1989). 1.4 The retinal image 1.3.4 TRANSMISSION OF THE OCULAR MEDIA For a variety of reasons, the transmissivity of the ocular media has been of interest, more recently because of concern for possible damage from exposure to intense sources. For decades the data accepted as authoritative came from the study by Ludvigh and McCarthy (1938). It formed the basis for the confirmation that the energy exchange at absolute visual threshold involved only a handful of photons (Hecht et al. 1942). Wavelength dependency of light absorption in the media became an issue in the characterization of retinal photopigments, one of the most important research enterprises of vision science in the middle of the twentieth century (Rushton 1959, Wald 1964). 1.3.5 RETINAL OPTICS interest, therefore, is the attempt by Ingelstam (1956) to show that the ultramicroscopic structure of receptors, which had just been discovered, might allow wavelength-dependent differential energy concentration. Most of these conjectures were laid to rest by Brindley and Rushton’s (1959) demonstration that to the human observer colors looked the same whether light entered the retina from the front or the back. The effect of the concentration of photopigments on their absorption spectrum—called selfscreening—must, however, be considered in color vision theory (Brindley 1960) and probably plays a role in the Stiles–Crawford effect of the second kind (Stiles 1939), color changes associated with direction of incident light. 1.4 THE RETINAL IMAGE 1.4.1 ABERRATIONS OF THE EYE A theoretical approach to the monochromatic aberrations in an optical system requires adequate knowledge of the optical parameters, position and curvature of the surfaces, and refractive index of the media. Because the precision needed to estimate image quality by ray tracing was lacking, this topic of visual optics was largely unattended until it was, so to speak, turned upside down quite recently by nulling out the aberrations. There was a brief flurry of activity centered on spherical aberration, when it was fingered to account for night myopia (Koomen et al. 1951), of practical importance during the Second World War. The enlarged pupil in the scotopic state allows light to enter into the eye through regions manifesting spherical aberration, but the more likely explanation of accommodation activity in empty fields (Otero and Aguilar 1951) won out. In a curious interlude, a quite adequate experimental determination of the eye’s spherical aberration (Ivanoff 1953) was marred by inclusion of a point derived from the wrong supposition that the eye was always focused precisely on the target plane. When this is corrected (Westheimer 1955), outlines of spherical aberration across the pupil looked regular. Because it needs to be factored into the stimulus situation in color vision research, vision researchers throughout the twentieth century remained aware of the eye’s chromatic aberration (Hartridge 1918, Ames and Proctor 1921). Axial chromatic aberration (Wald and Griffin 1947) was mostly seen consonant with that of eye media with the dispersion of water. To obviate possible effects of chromatic aberration in color vision research, an “achromatizing lens” with the reverse of the eye’s chromatic aberration was designed (Bedford and Wyszecki 1957). During the same period, the role of lateral chromatic aberration of the eye in engendering spurious stereoscopic disparity was given due consideration (Vos 1960), but some inadequacies in the explanation remain. 1.4.2 QUALITY OF THE RETINAL IMAGE Helmholtz was fully aware that the central issue and best descriptor in the specification of the quality of the retinal image is the light distribution at a sharp target edge, though it took a little while for the realization that the point-spread function is even more basic. The most influential contributor at the beginning Introduction In the vertebrate, before it reaches the receptors, light has to traverse several retinal layers that therefore have to be essentially transparent, not necessarily a quality automatically associated with active neural tissue. Haidinger’s brushes, an entoptic phenomenon, have their origin in retinal optical structure (Naylor and Stanworth 1954). Myelination of the ganglion cell axons, helpful in enhancing velocity of action potentials, does not start till they exit the eyeball at the optic disk. The vascular tree of Purkinje, a prominent feature of the fundus, is somehow compensated for and made visible only by special tricks. The central region of the retina in the primate is suffused by a pigment, selectively absorbing light of some wavelengths. It seems to have a role in Haidinger’s brushes (Bone and Landrun 1984, Mission 1993), but whether it is the origin of the entoptic phenomenon known as Maxwell’s spot (Maxwell 1890/1965, p. 278) has been subject of an interesting debate (Polyak 1941, Walls and Mathews 1952). Of great significance are its possible protective properties (Snodderly 1995). Optics becomes critical however, in the operation of receptor cells, whose diameter is of the order of the wavelength of light. A start was made in the 1840s by Ernst Brücke, at the time Helmholtz’s fellow student in Johannes Müller’s Institute in Berlin, who made the observation that rodlike retinal receptor cells acted like light guides. He seems not to have published it; all we have is Helmholtz’s (1866) report and the comment that light once it had entered a receptor and impinged on the cylindrical boundary separating media of high from low refractive index would undergo total reflection and proceed further along the receptor and not leave it. Receptor optics became mainstream with the discovery of the retinal directional sensitivity by Stiles and Crawford (1933) and the conjecture by Toraldo (1949) of retinal cones being wave guides. This set into motion extensive research activity, still ongoing. The state of the subject is well captured in the contributions to Enoch and Tobey’s Vertebrate Receptor Optics (1981). Whereas rods and their rhodopsin photopigment had been fully identified with scotopic vision, the same could not be said about cones and the cone pigments till the 1960s. Before that, because there was no firsthand knowledge of the phototransduction that underlies color vision, the possibility remained open that there was only a single cone pigment and that wavelength analysis came about through an intracellular filtering process, as indeed is the case with oil drops in birds (Walls 1942). Of historical 5 Introduction 6 History of physiological optics in the twentieth century of the century was Hamilton Hartridge (1922), and it is hard to imagine anyone doing better at a time before the idea of direct measurement took hold. Assuming that the shape of the pointspread function was Gaussian and making rather good guesses of the parameter, Fry and Cobb (1935) were able to achieve some synthesis between image light spread and thresholds for simple line targets. In retrospect, the direction of future development was clearly foreshadowed by exceedingly insightful indirect approaches to retinal image quality by LeGrand (1935) using interference and Shlaer (1937) employing what is tantamount to Abbe’s theory of microscope resolution. But, at the start of my career in vision science just after the Second World War, these were not adequately understood or appreciated. In their place, the interest was in direct measurements, first in an approachable if not particularly informative animal preparation, the excised steer eye, expeditiously brought from the abattoir to the lab, as Jay Enoch, one of the collaborators explained to me (Boynton et al. 1954). Needless to say, light spread was very extensive, making one the researchers wonder why, if the image is so bad, visual acuity is so good (DeMott 1959). As the research during the remainder of the century, and continuing to the present, has made clear, such a proposition was ill-posed—the need instead was to pursue the question of how good, in the end, the retinal image might actually be, with all the experimental prowess that can be marshaled. The most interesting and productive laboratory of the time was at the Institut d’Optique in Paris where Arnulf and his students were in daily contact with the change in approach to the theory of optics that began with Duffieux’s (1946) paperback. To call the turn to Fourier optics revolutionary would be an exaggeration, because it is implicit in the resolution formulations of Rayleigh and Abbe and Fourier’s Lehrsatz is explicitly used on p. 185 of Born (1933). In the single most significant paper in the subject of retinal imagery of the twentieth century, Francoise Flamant (1955) used the principle of the ophthalmoscope to measure the width of the reflected image of a narrow slit. Being familiar with the theorem that convolution becomes multiplication in the Fourier domain, she undid the double convolution due to the light traversing the eye media twice by taking the square root of its Fourier transform. Needless to say, Flamant’s results were much closer to the human optics than those on the excised steer eye. In a sequence of more and more sophisticated experiments using photomultiplier tubes in place of Flamant’s grainy photographic film (Westheimer and Campbell 1962, Campbell and Gubisch 1966), objective data were accumulated on the optical image quality of the normal human eye that proved quite compatible with psychophysical ones employing the principle of interference fringes (Westheimer 1960, Campbell and Green 1965). Conjectures on hypothetical image sharpening mechanisms with their improbable information-theoretical basis could be discounted (Gubisch 1967). 1.4.3 OPTICAL TRANSFER FUNCTION Nowhere is the complementarity of the traditional spatial and the modern spatial-frequency descriptions of imagery more evident than in counterposing the image light spread and the optical transfer functions. They are Fourier transforms of each other and therefore have their x-axes point in opposite directions: light spread over extensive regions tends toward infinite distances in the image plane but toward zero (the DC point) in the spatialfrequency spectrum. In principle, the diffraction image of a point source with a round pupil never stays at zero intensity, though its central lobe, the Airy disk, has a well-defined diameter. But the spatial-frequency spectrum has a distinct cutoff point beyond which there is no representation of grating targets. When this became understood and increasingly popular from the middle of the twentieth century on, the resolution limit of optical devices was better appreciated and could be related to the electrical circuits to which they were increasingly being coupled. Yet the fundamental distinction always needs pointing out: on the one hand, a firm cutoff spatial frequency in optical imagery and, on the other, the sloping transfer function, in principle never quite reaching zero transmission in electronics. The eye’s actual optical transfer function exemplified by the original one provided in the Campbell and Green study of 1965 included the effect of aberrations and the pupil diameter, but still needed extension to include not only amplitude but also phase, discarded in the power spectrum. For many years, from the seminal paper by Schade (1956) and the widely quoted data of van Nes and Bouman (1967) on, the majority of interpretations of the modulation transfer function of the whole visual system failed to stress that it lacked phase information and hence did not allow a unique description of light spread from the power spectrum. It took almost a couple of decades from the first enunciation of the Fourier theory of vision till the explicit demonstration that phase was more important than amplitude (Piotrovsky and Campbell 1982). Yet it has been shown by Hopkins (1955) and Steel (1956) that defocus manifests itself prominently in the phase of the optical transfer function. 1.4.4 STREHL RATIO Attempts at capturing image quality in a single number go back to Strehl (1895), a high school teacher with an abiding interest in telescope design, who suggested the ratio of the height of the actual point-spread function at its center to that of the diffraction image, generally the Airy disk, defined by the instrument’s aperture and the wavelength of light. It was conservatively estimated at 0.2 (Gubisch 1967) in a good eye, but in practice may be much less, because even a miniscule level of stray light (see below) at outlying image distances, covering as it does large retinal areas, would be integrated in the constant volume of light involved in computing the Strehl ratio. Areal summation of light probably makes a low value of the Strehl ratio not as severe a visual handicap as it may appear. 1.4.5 STRAY LIGHT Whereas the shape of the central lobe of the point-spread function is an important factor in visual acuity, its long tail plays a role in a different visual phenomenon, glare. The veiling effect of bright sources in quite remote retinal areas can have deleterious influence on some visual tasks and early on in the twentieth century attempts were made to distinguish between optical and physiological causes (Holladay 1927, Stiles and Crawford 1937). This required the estimation of the retinal illuminance distribution caused by light scatter in the eye, which also, depending on the 1.6 Spurt at the end of the twentieth century wavelength and the red reflectance of the fundus, could act as an integrating sphere. The visual system has been used as a null detector to calibrate the threshold-raising effect of a uniform field of known luminance against that of distant outer zones of bright glare sources. This has yielded useful contributions to our knowledge of the quality of the retinal image (Fry and Alpern 1953, Vos 1962). 1.5 OPHTHALMIC INSTRUMENTATION 1.5.1 OPHTHALMOSCOPY The introduction of the ophthalmoscope by Helmholtz led to an unsurpassed blossoming in the diagnosis of eye diseases and, when the optical industry was ready at the turn of the twentieth century, to the development of high-performing instruments. Successively versions were self-luminous, reflex-free, and stereoscopic. The Thorner design made by Busch was pitted against the Gullstrand version made by Zeiss. 1.5.2 OPTOMETERS AND AUTOMATIC OBJECTIVE REFRACTOMETERS In order to clearly visualize the fundus in ophthalmoscopy, the patient’s refractive error needs to be compensated. SchmidtRimpler in 1877 used this phenomenon to obtain an objective measure of the refractive error. Since then there have been many versions of what are called optometers or refractometers or refractionometers. E.F. Fincham’s design of a Coincidence Optometer is perhaps the highlight of this trend (Fincham 1937b) early in the century. They depended on an observer detecting either the sharpness of an image or, as in Fincham’s instrument, the alignment of two lines each carried by a separate beam through a different region of the eye’s pupil. The automatic recording infrared optometer of Campbell and Robson (1959) put an end to an era when records of the eye’s accommodative changes were secured by cinematography of the Purkinje image from the anterior surface of the lens (Allen 1949) and the emphasis shifted to using light reflected from the fundus. With the advent of modern optical and electronic components, automated objective refractometers became compact and user-friendly and by the turn of the twenty-first century had established themselves firmly in the eye clinic. Documentation of this development can be found elsewhere. 1.6 SPURT AT THE END OF THE TWENTIETH CENTURY Introduction The narrative so far, covering developments in physiological optics narrowly defined to include the optical properties of human eye in the major portion of twentieth century, was informed by the author’s personal experience: undergraduate training based on the state of knowledge prior to the outbreak of the Second World War, his active involvement in the discipline over the rest of the century, and his personal acquaintance with all the major participants in the story. Much of the groundwork was laid in the British Isles by Smith and Porterfield in the eighteenth century and by Thomas Young, J.C. Maxwell, Lord Rayleigh, Airy, and others in the nineteenth century and preserved in ophthalmological (Duke-Elder 1932) and optometric texts (Laurence 1926, Emsley 1939). Specifically deserving of mention as upholding and furthering the tradition in the twentieth century are E.F. Fincham (1893–1963) and Arthur G. Bennett (1912–1994). On the continent, where Kepler, Descartes, and Scheiner had earlier clarified the image-forming properties of the eye, the work of the giants, Gauss and Listing (1808–1882), Purkinje, and Helmholtz, soon percolated down to the clinic and then to productive collaboration with optical industry. Von Graefe (1828–1870), Donders, Landolt, Snellen, and Gullstrand held on and maintained the tradition, and so did, at least in the realm of scholarship, Moritz von Rohr (1868–1940) and Armin von Tschermak (1870–1952) in the next generation. Emblematic of what followed is Max Born (1882–1970) and his magisterial textbook Optik. Removed in 1933 from their native habitat, they reemerged in another, more welcoming language and environment and with immensely augmented success and influence. Principles of Optics by Born and Wolf is now in its seventh edition. Important laboratories in the middle of the twentieth century were located in the Netherlands, sparked by Maarten Bouman (1919–2011), and at the Istituto Nazionale di Ottica in Arcetri-Florence under the auspices of the Ronchi family. In Paris at the Institut d’Optique, where Marechal and others (Fleury et al. 1949) dug deeply into the fundamentals of image formation, diffraction, Fourier filtering, and apodization (Dossier 1954), Albert Arnulf (1898–1984) led a group of investigators who in the 1950s were unmatched in the point of attack and skill in physiological optics experiments. Fergus Campbell once told me that whenever he started a research project, he found that Arnulf had been there before. Cambridge, England, had been the site of Thomas Young’s major discovery. In the middle of the twentieth century, it saw an extraordinary blossoming of vision research and, as the host of innumerable students and visitors, predominantly from the United States, had a lasting international impact. Of the several centers in the United States, mention should be made of the Dartmouth Eye Institute (Burian 1948) where collaboration with a research arm of the American Optical Company resulted in the design of ophthalmic diagnostic and corrective devices. The work of scientists Paul Boeder and Kenneth N. Ogle (1902–1968), later at the Mayo Clinic, helped give it an optical basis. In the same period, vision research in general, and often physiological-optical in substance, was prominent at Columbia University, where Selig Hecht (1882–1947) in Biophysics and C.H. Graham (1906–1971) in Psychology operated well-supported laboratories and their many students spread a research culture characterized by upto-date methodology and experimental rigor. The same applied to Lorrin Riggs (1912–2008) at the Psychology Department of Brown University and Glenn A. Fry (1908–1996) at the Ohio State University School of Optometry. The dramatic transformation that took place in the last third of the twentieth century had its origin less in any theoretical or conceptual changes than in the prodigious advances in the materials from which optical and electronic components are constructed: optical fibers, crystals, transistors, integrated 7

Author Pablo Artal Isbn 9781482237856 File size 24MB Year 2017 Pages 449 Language English File format PDF Category Biology Book Description: FacebookTwitterGoogle+TumblrDiggMySpaceShare Handbook of Visual Optics offers an authoritative overview of encyclopedic knowledge in the field of physiological optics. It builds from fundamental concepts to the science and technology of instruments and practical procedures of vision correction, integrating expert knowledge from physics, medicine, biology, psychology, and engineering. The chapters comprehensively cover all aspects of modern study and practice, from optical principles and optics of the eye and retina to novel ophthalmic tools for imaging and visual testing, devices and techniques for visual correction, and the relationship between ocular optics and visual perception.     Download (24MB) Handbook of Visual Optics, Volume Two Bioluminescence: Methods and Protocols (3rd edition) Nanobiomaterials Handbook Advanced Biophotonics: Tissue Optical Sectioning Laser Imaging and Manipulation in Cell Biology Load more posts

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