Clinical Optics

Clinical Optics is intended primarily for use by optometry students, though it could also prove useful for the training of optometric technicians and dispensing opticians. This book is organized into thirteen chapters. These chapters cover most aspects of ophthalmic optics or clinical optics including the design and dispensing of eyewear, the types for lenses suitable for correcting high refractive errors, the optical principles governing low vision lenses and the importance of absorptive lenses and lens coatings for eye protection against radiation. This book will be of interest to optometry students and to those involved in the training of optometric technicians and dispensing opticians.

ContentsPreface Introduction. Sign Convention, Nomenclature, and Notation 0.1 Sign Convention 0.2 Nomenclature 0.3 Notation Chapter One Ophthalmic Lens Materials Glass 1.1 History of Glassmaking 1.2 The Development of Optical Glass 1.3 The Manufacture of Optical Glass 1.4 Varieties of Optical Glass 1.5 Desirable Characteristics and Defects of Optical Glass Plastic Materials 1.6 Introduction 1.7 Manufacturing Processes 1.8 Development of Optical Plastics 1.9 Manufacture of Plastic Lenses 1.10 Optical and Physical Properties of Plastic Lenses The Strength of Lens Materials 1.11 FDA Policies 1.12 The Strength of Glass 1.13 Methods of Tempering Glass Lenses 1.14 Impact Resistance of Plastic Lenses 1.15 Lenses for Occupational and Educational Use References Questions Chapter Two Characteristics of Ophthalmic Lenses Physical Characteristics 2.1 Curvature 2.2 Surfaces of Revolution 2.3 Relationship between Curvature and Refracting Power of a Surface 2.4 The Lens Measure 2.5 Lens Form: Spherical Lenses 2.6 Lens Form: Cylindrical and Toric Lenses 2.7 Lens Blanks and Base Curves 2.8 Specification of Cylinder Axes 2.9 Prescription Writing and Transposition Optical Characteristics 2.10 Basic Terminology 2.11 Image Formation by a Spherical Lens 2.12 Image Formation by Cylindrical and Toric Lenses 2.13 Terminology and Basic Concepts Regarding Image Formation by a Lens 2.14 Dimensional Aspects of the Conoid of Sturm 2.15 Misconceptions Concerning Astigmatic Image Formation 2.16 The Spherical Equivalent 2.17 Power in an Oblique Meridian of a Cylindrical Lens 2.18 Power in an Oblique Meridian of aToric Lens 2.19 Obliquely Crossed Cylinders 2.20 Astigmatism due to Lens Tilt 2.21 The Maddox Rod References Questions Chapter Three. Power Specification and Measurement Power Specification 3.1 Introduction 3.2 Approximate Power 3.3 Back Vertex Power 3.4 Front Vertex Power, or Neutralizing Power 3.5 Equivalent Power 3.6 Effective Power Power measurement 3.7 Hand Neutralization 3.8 The Lensometer 3.9 Lensometer Calibration, Alignment, and Measurement Errors 3.10 Projection Lensometers 3.11 Automatic Lensometers Relationships Between Lens Power and Lens Thickness 3.12 The Sagitta Formula 3.13 Formula Relating Power to Center Thickness and Edge Thickness 3.14 Thickness Calculations for Cylindrical and Sphero-cylindrical Lenses Reference Questions Chapter Four Ophthalmic Prisms and Decentration 4.1 Terminology 4.2 Refracting Power of a Prism 4.3 Specification of the Power of an Ophthalmic Prism 4.4 Relationship between Refracting Angle and Angle of Deviation 4.5 Effects of Prisms on Movements of the Eyes 4.6 Prentice's Rule 4.7 Oblique Prismatic Effects 4.8 Obliquely Crossed Prisms 4.9 Effective Power of a Prism in an Oblique Meridian 4.10 Specification of Prismatic Effects: The Major Reference Point 4.11 Specification of Lens and Frame Sizes 4.12 Prismatic Power and Thickness 4.13 Thickness of a Lens/Prism 4.14 Prismatic Effects of Cylindrical Lenses 4.15 Decentration 4.16 Effects of Prisms on the Eyes 4.17 Effectivity of a Prism 4.18 Risley Prisms 4.19 Fresnel Press-on Prisms References QuestionsChapter Five. The Correction of Ametropia 5.1 The Schematic Eye 5.2 Emmetropia and Ametropia 5.3 The Far and Near Points of Accommodation 5.4 The Correction of Spherical Ametropia 5.5 Range and Amplitude of Accommodation 5.6 Spectacle Refraction versus Ocular Refraction 5.7 Spectacle Accommodation versus Ocular Accommodation 5.8 Accommodation and Effectivity in Anisometropia 5.9 Accommodation and Effectivity in Astigmatism 5.10 Retinal Image Size in Uncorrected Ametropia 5.11 Retinal Image Size in Corrected Ametropia References Questions Chapter Six. Aberrations and Ophthalmic Lens Design Introduction 6.1 Laws of Geometrical Optics Chromatic Aberration and Achromatic Lenses 6.2 Chromatic Aberration 6.3 Chromatic Dispersion 6.4 Chromatic Aberration in Prisms 6.5 Achromatic Prisms 6.6 Chromatic Aberration in Lenses 6.7 Achromatic Lenses The Monochromatic Aberrations 6.8 Spherical Aberration 6.9 Coma 6.10 Oblique Astigmatism 6.11 Curvature of Image 6.12 Distortion Principles of Lens Design 6.13 Introduction 6.14 Lens Design Variables 6.15 Design Assumptions 6.16 The Base Curve of a Lens History and Evolution of Lens Design 6.17 Spherical Lenses 6.18 Sphero-Cylindrical Lens Design 6.19 Negative versus Positive Toric Lenses 6.20 Design of High Plus Lenses The Optometrists Role in Lens Design 6.21 Changes in the Optical Industry and in ANSI Standards 6.22 Base Curve Specification References Questions Chapter seven. Absorptive Lenses and Lens Coatings Effects of Radiation on the Eye 7.1 The Nature of Light 7.2 The Visible Spectrum 7.3 Classification of Radiation Effects 7.4 Concentration of Radiant Energy by the Eye 7.5 Absorption of Radiation by the Ocular Tissues 7.6 Effects of Ultraviolet Radiation 7.7 Effects of Infrared Radiation 7.8 The Effects of Visible Radiation 7.9 Other Forms of Radiation 7.10 Recommended Levels of Retinal Illumination Absorptive Lenses 7.11 Reflection, Absorption, and Transmission 7.12 Opacity 7.13 Density 7.14 Methods of Manufacturing Absorptive Lenses 7.15 Categories of Absorptive Lenses and Specification of Transmission 7.16 General-Wear Lenses Absorbing the Spectrum Evenly 7.17 Lenses That Selectively Absorb Ultraviolet Radiation While Transmitting the Visible Spectrum in a Uniform Manner 7.18 Lenses That Selectively Absorb Both Ultraviolet and Infrared Radiation While Absorbing a Substantial Amount of Visible Radiation in a Relatively Uniform Manner 7.19 Lenses That Selectively Absorb Portions of the Visible Spectrum 7.20 Absorptive Lenses Designed for Occupational Use 7.21 Photochromic Lenses 7.22 Lens Thickness and Transmission 7.23 Prescribing Absorptive Lenses 7.24 Miscellaneous Absorptive Lenses Lens Reflections and Coatings 7.25 Refleaions from Spectacle Lens Surfaces 7.26 Types of Surface Reflections 7.27 Methods of Controlling Surface Reflections 7.28 Antireflective Coatings 7.29 Optical Principles of Antireflective Coatings 7.30 Production of Antireflective Coatings 7.31 Reflections Annoying to an Observer References Questions Chapter Eight. Multifocal Lenses Physical Characteristics 8.1 History and Development of Multifocal Lenses 8.2 Fused Bifocal Lenses 8.3 One-Piece Bifocal Lenses 8.4 Double-Segment Bifocals 8.5 "Minus Add" Bifocal 8.6 Trifocal Lenses 8.7 Plastic Multifocal Lenses Multifocal Lens Manufacturing Processes 8.8 Glass Multifocals 8.9 Plastic Multifocals Optical Principles of Multifocal Lens Design 8.10 Powers of the Distance and Reading Portions 8.11 One-Piece Bifocals 8.12 Fused Bifocals Performance Characteristics 8.13 Vertical Placement of the Optical Center of the Segment 8.14 Lateral Placement of the Optical Center of the Segment 8.15 Differential Displacement (Image Jump) 8.16 The Zone of Confusion 8.17 Differential Displacement at the Reading Level 8.18 Total Displacement at the Reading Level 8.19 Transverse Chromatic Aberration Clinical Considerations 8.20 Theories of Bifocal Selection 8.21 Segment Size and Shape 8.22 Horizontal Prismatic Effects 8.23 Differential Vertical Prismatic Effects at the Reading Level 8.24 Ordering and Dispensing Bifocals 8.25 Verification of Bifocals 8.26 Prescribing and Fitting Double-Segment Bifocals 8.27 Prescribing and Fitting Trifocals Invisible bifocals and progressive addition Lenses 8.28 Invisible Bifocals 8.29 Blended Bifocals 8.30 Progressive Addition Lenses 8.31 Patient Selection and Dispensing Considerations References Questions Chapter Nine. Eyewear Design and Dispensing Spectacle Frames and Mountings 9.1 Historical Introduction 9.2 Modern Frames and Mountings 9.3 Metal Frame and Mounting Materials 9.4 Plastic Frame Materials 9.5 Bridge and Temple Styles Frame Selection and Ordering Materials 9.6 Measuring Interpupillary Distance 9.7 Frame Selection 9.8 Fitting Principles 9.9 Frame Alignment 9.10 Frame and Mounting Specifications 9.11 Lateral Placement of Optical Centers 9.12 Vertical Placement of Optical Centers 9.13 Centering Problems and Solutions 9.14 Bifocal Segment Inset 9.15 Prescription Order Forms Verification and Dispensing 9.16 Verification 9.17 Dispensing and Adjusting References Questions Chapter Ten. Anisometropia and Aniseikonia Anisometropia 10.1 Problems Resulting from Anisometropia 10.2 Horizontal Prismatic Effects 10.3 Differential Vertical Prismatic Effects at the Reading Level Aniseikonia 10.4 Introduction 10.5 Etiology of Aniseikonia 10.6 Significance of Aniseikonia 10.7 The Spectacle Magnification Formula 10.8 Clinical Application of the Spectacle Magnification Formula 10.9 Comparison of Spectacle and Contact Lens Magnification 10.10 Spectacle Magnification in Astigmatism 10.11 Relative Spectacle Magnification 10.12 Relative Spectacle Magnification in Axial Ametropia 10.13 Relative Spectacle Magnification in Refractive Ametropia 10.14 Relative Spectacle Magnification in Astigmatism 10.15 The Dilemma of Relative Spectacle Magnification 10.16 Clinical Considerations in Anisometropia and Astigmatism Prescribing to Eliminate or Minimize Induced Aniseikonia 10.17 Indications of the Presence of Aniseikonia 10.18 Measurement of Image Size Differences 10.19 Estimating the Amount of Aniseikonia 10.20 Avoiding or Minimizing Induced Aniseikonia 10.21 Prescribing and Lens Design 10.22 The Use ofEikonic Lenses in Fit-Over Form 10.23 Frame Selection for Eikonic Lenses 10.24 Aniseikonia: Clinical Considerations in Anisometropia and Astigmatism References Questions Chapter Eleven. Lenses for High Refractive Errors Lenses for Aphakia and High Hyperopia 11.1 Management of the Cataract Patient 11.2 Optical Consequences of Cataract Surgery 11.3 Predicting the Power of an Aphakic Lens 11.4 Problems with Aphakic Spectacles 11.5 Parameters of Aphakic Lenses 11.6 Aphakic Lens Design 11.7 Frames for Aphakic Lenses 11.8 The Unilateral Aphakic 11.9 Determining^the Final Aphakic Prescription 11.10 The High Hyperope Lenses for High Myopia 11.11 Problems Caused by High Minus Lenses 11.12 Minimizing Edge Thickness 11.13 Minimizing Edge Reflections 11.14 Lenticular Lenses 11.15 Fresnel Press-on Lenses References Questions Chapter Twelve. Optical Principles of Lenses for Low Vision 12.1 Methods of Providing Magnification Optical Aids for Distance Vision 12.2 Afocal Telescopes 12.3 Headborne Telescopic Systems 12.4 Nonprescription Telescopes Optical Aids for Near Vision 12.5 Microscopic Lenses 12.6 Telescopic Lenses for Near Vision 12.7 Hand Magnifiers 12.8 Stand Magnifiers 12.9 The Paperweight Magnifier References Questions Chapter Thirteen. Optics of Contact Lenses Basic Contact Lens Optics 13.1 The Contact Lens as a Thick Lens 13.2 The Effective Power of a Contact Lens 13.3 Calibration of the Keratometer The Contact Lens/Eye Optical System 13.4 The Contact Lens on the Eye 13.5 Over-refraction 13.6 Contact Lenses and Corneal Astigmatism 13.7 Fitting Steeper or Flatter Than the Cornea 13.8 The Optics of Bifocal Contact Lenses 13.9 Residual Astigmatism and Its Correction 13.10 Magnification Effects of Contact Lenses Effects of Contact Lenses on Binocular Vision 13.11 Accommodative Demand 13.12 Accommodative Convergence 13.13 Prismatic Effects 13.14 Prescribing Prism in a Contact Lens Aberrations and Field of View 13.15 Aberrations 13.16 Field of View Aphakia 13.17 Aphakic Contact Lenses Instrumentation 13.18 The Radiuscope References Questions Answers to Questions Index

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Theodore Grosvenor

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