Clinical Optics (eBook)

Troy E. Fannin, Theodore Grosvenor (Autoren)

eBook Download: PDF

2013 | 1. Auflage
480 Seiten
Elsevier Science (Verlag)
978-1-4831-9259-8 (ISBN)

Infos

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.

Adjunct Professor, Pacific University College of Optometry, Forest Grove, OR; Professor Emeritus, Indiana University School of Optometry, Bloomington, IN; Professor Emeritus, University of Houston College of Optometry, Houston, TX

Inhalt

Front Cover 1
Clinical Optics 4
Copyright Page 5
Table of Contents 6
Preface 12
INTRODUCTION: Sign Convention, Nomenclature, and Notation 14
0.1. Sign Convention 15
0.2. Nomenclature 15
0.3. Notation 16
Reference 17
Bibliography 17
CHAPTER 1. Ophthalmic Lens Materials 20
1.1. History of Glassmaking 21
1.2. The Development of Optical Glass 22
1.3. The Manufacture of Optical Glass 23
1.4. Varieties of Optical Glass 23
1.5. Desirable Characteristics and Defects of Optical Glass 25
1.6. Introduction 26
1.7. Manufacturing Processes 26
1.8. Development of Optical Plastics 27
1.9. Manufacture of Plastic Lenses 28
1.10. Optical and Physical Properties of Plastic Lenses 28
1.11. FDA Policies 30
1.12. The Strength of Glass 31
1.13. Methods of Tempering Glass Lenses 32
1.14. Impact Resistance of Plastic Lenses 34
1.15. Lenses for Occupational and Educational Use 35
References 35
Questions 36
CHAPTER 2. Characteristics of Ophthalmic Lenses 38
2.1. Curvature 39
2.2. Surfaces of Revolution 41
2.3. Relationship between Curvature and Refracting Power of a Surface 42
2.4. The Lens Measure 42
2.5. Lens Form: Spherical Lenses 44
2.6. Lens Form: Cylindrical and Toric Lenses 44
2.7. Lens Blanks and Base Curves 46
2.8. Specification of Cylinder Axes 46
2.9. Prescription Writing and Transposition 46
2.10. Basic Terminology 49
2.11. Image Formation by a Spherica! Lens 52
2.12. Image Formation by Cylindrical and Toric Lenses 52
2.13. Terminology and Basic Concepts Regarding Image Formation by a Lens 52
2.14. Dimensional Aspects of the Conoid of Sturm 54
2.15. Misconceptions Concerning Astigmatic Image Formation 56
2.16. The Spherical Equivalent 57
2.17. Power in an Oblique Meridian of a Cylindrical Lens 58
2.18. Power in an Oblique Meridian of a Toric Lens 60
2.19. Obliquely Crossed Cylinders 61
2.20. Astigmatism due to Lens Tilt 68
2.21. The Maddox Rod 69
References 71
Questions 71
CHAPTER 3. Power Specification and Measurement 74
3.1. Introduction 75
3.2. Approximate Power 76
3.3. Back Vertex Power 76
3.4. Front Vertex Power, or Neutralizing Power 77
3.5. Equivalent Power 79
3.6. Effective Power 83
3.7. Hand Neutralization 84
3.8. The Lensometer 88
3.9. Lensometer Calibration, Alignment, and Measurement Errors 96
3.10. Projection Lensometers 98
3.11. Automatic Lensometers 98
3.12. The Sagitta Formula 99
3.13. Formula Relating Power to Center Thickness and Edge Thickness 100
3.14. Thickness Calculations for Cylindrical anc' Sphero-Cylindrical Lenses 102
Reference 104
Questions 104
CHAPTER 4. Ophthalmic Prisms and Decentration 106
4.1. Terminology 107
4.2. Refracting Power of a Prism 107
4.3. Specification of the Power of an Ophthalmic Prism 108
4.4. Relationship between Refracting Angle and Angle of Deviation 110
4.5. Effects of Prisms on Movements of the Eyes 110
4.6. Prentice's Rule 112
4.7. Oblique Prismatic Effects 115
4.8. Obliquely Crossed Prisms 117
4.9. Effective Power of a Prism in an Oblique Meridian 118
4.10. Specification of Prismatic Effects: The Major Reference Point 119
4.11. Specification of Lens and Frame Sizes 119
4.12. Prismatic Power and Thickness 121
4.13. Thickness of a Lens/Prism 121
4.14. Prismatic Effects of Cylindrical Lenses 123
4.15. Decentration 126
4.16. Effects of Prisms on the Eyes 131
4.17. Effectivity of a Prism 132
4.18. Risley Prisms 133
4.19. Fresnel Press-on Prisms 134
References 136
Questions 136
CHAPTER 5. The Correction of Ametropia 138
5.1. The Schematic Eye 139
5.2. Emmetropia and Ametropia 140
5.3. The Far and Near Points of Accommodation 142
5.4. The Correction of Spherical Ametropia 143
5.5. Range and Amplitude of Accommodation 144
5.6. Spectacle Refraction versus Ocular Refraction 147
5.7. Spectacle Accommodation versus Ocular Accommodation 149
5.8. Accommodation and Effectivity in Anisometropia 152
5.9. Accommodation and Effectivity in Astigmatism 154
5.10. Retinal Image Size in Uncorrected Ametropia 155
5.11. Retinal Image Size in Corrected Ametropia 155
References 157
Questions 158
CHAPTER 6. Aberrations and Ophthalmic Lens Design 160
6.1. Laws of Geometrical Optics 161
6.2. Chromatic Aberration 162
6.3. Chromatic Dispersion 163
6.4. Chromatic Aberration in Prisms 164
6.5. Achromatic Prisms 164
6-6- Chromatic Aberration in Lenses 165
6.7. Achromatic Lenses 166
6.8. Spherical Aberration 167
6.9. Coma 168
6.10. Oblique Astigmatism 169
6.11. Curvature of Image 171
6.12. Distortion 174
6.13. Introduction 175
6.14. Lens Design Variables 176
6.15. Design Assumptions 178
6.16. The Base Curve of a Lens 179
6.17. Spherical Lenses 181
6.18. Sphero-Cylindrical Lens Design 185
6.19. Negative versus Positive Toric Lenses 186
6.20. Design of High Plus Lenses 186
6.21. Changes in the Optical Industry and in ANSI Standards 187
6.22. Base Curve Specification 188
References 189
Questions 189
CHAPTER 7. Absorptive Lenses and Lens Coatings 192
7.1. The Nature of Light 193
7.2. The Visible Spectrum 195
7.3. Classification of Radiation Effects 196
7.4. Concentration of Radiant Energy by the Eye 196
7.5. Absorption of Radiation by the Ocular Tissues 197
7.6. Effects of Ultraviolet Radiation 198
7.7. Effects of Infrared Radiation 198
7.8. The Effects of Visible Radiation 199
7.9. Other Forms of Radiation 200
7.10. Recommended Levels of Retinal Illumination 200
7.11. Reflection, Absorption, and Transmission 201
7.12. Opacity 202
7.13. Density 203
7.14. Methods of Manufacturing Absorptive Lenses 204
7.15. Categories of Absorptive Lenses and Specification of Transmission 207
7.16. General-Wear Lenses Absorbing the Spectrum Evenly 207
7.17. Lenses That Selectively Absorb Ultraviolet Radiation While Transmitting the Visible Spectrum in a Uniform Manner 211
7.18. Lenses That Selectively Absorb Both Ultraviolet and Infrared Radiation While Absorbing a Substantial Amount of Visible Radiation in a Relatively Uniform Manner 216
7.19. Lenses That Selectively Absorb Portions of the Visible Spectrum 223
7.20. Absorptive Lenses Designed for Occupational Use 224
7.21. Photochromic Lenses 226
7.22. Lens Thickness and Transmission 232
7.23. Prescribing Absorptive Lenses 234
7.24. Miscellaneous Absorptive Lenses 235
7.25. Reflections from Spectacle Lens Surfaces 236
7.26. Types of Surface Reflections 237
7.27. Methods of Controlling Surface Reflections 239
7.28. Antireflective Coatings 239
7.29. Optical Principles of Antireflective Coatings 241
7.30. Production of Antireflective Coatings 242
7.31. Reflections Annoying to an Observer 243
References 244
Questions 245
CHAPTER 8. Multifocal Lenses 246
8.1. History and Development of Multifocal Lenses 247
8.2. Fused Bifocal Lenses 251
8.3. One-Piece Bifocal Lenses 253
8.4. Double-Segment Bifocals 254
8.5. "Minus Add'' Bifocal 254
8.6. Trifocal Lenses 255
8.7. Plastic Multifocal Lenses 255
8.8. Glass Multifocals 257
8.9. Plastic Multifocals 259
8.10. Powers of the Distance and Reading Portions 260
8.11. One-Piece Bifocals 260
8.12. Fused Bifocals 261
8.13. Vertical Placement of the Optical Center of the Segment 265
8.14. Lateral Placement of the Optical Center of the Segment 266
8.15. Differential Displacement (Image Jump) 268
8.16. The Zone of Confusion 270
8.17. Differential Displacement at the Reading Level 271
8.18. Total Displacement at the Reading Level 272
8.19. Transverse Chromatic Aberration 273
8.20. Theories of Bifocal Selection 276
8.21. Segment Size and Shape 277
8.22. Horizontal Prismatic Effects 279
8.23. Differential Vertical Prismatic Effects at the Reading Level 280
8.24. Ordering and Dispensing Bifocals 280
8.25. Verification of Bifocals 282
8.26. Prescribing and Fitting Double-Segment Bifocals 285
8.27. Prescribing and Fitting Trifocals 285
8.28. Invisible Bifocals 288
8.29. Blended Bifocals 289
8.30. Progressive Addition Lenses 290
8.31. Patient Selection and Dispensing Considerations 297
References 300
Questions 301
CHAPTER 9. Eyewear Design and Dispensing 304
9.1. Historical Introduction 305
9.2. Modern Frames and Mountings 305
9.3. Metal Frame and Mounting Materials 307
9.4. Plastic Frame Materials 308
9.5. Bridge and Temple Styles 309
9.6. Measuring Interpupillary Distance 311
9.7. Frame Selection 313
9.8. Fitting Principles 315
9.9. Frame Alignment 316
9.10. Frame and Mounting Specifications 319
9.11. Lateral Placement of Optical Centers 319
9.12. Vertical Placement of Optical Centers 320
9.13. Centering Problems and Solutions 322
9.14. Bifocal Segment Inset 323
9.15. Prescription Order Forms 324
9.16. Verification 326
9.17. Dispensing and Adjusting 328
References 331
Questions 331
CHAPTER 10. Anisometropia and Aniseikonia 334
10.1. Problems Resulting from Anisometropia 335
10.2. Horizontal Prismatic Effects 335
10.3. Differential Vertical Prismatic Effects at the Reading Level 336
10.4. Introduction 342
10.5. Etiology of Aniseikonia 342
10.6. Significance of Aniseikonia 344
10.7. The Spectacle Magnification Formula 345
10.8. Clinical Application of the Spectacle Magnification Formula 348
10.9. Comparison of Spectacle and Contact Lens Magnification 349
10.10. Spectacle Magnification in Astigmatism 350
10.11. Relative Spectacle Magnification 351
10.12. Relative Spectacle Magnification in Axial Ametropia 351
10.13. Relative Spectacle Magnification in Refractive Ametropia 353
10.14. Relative Spectacle Magnification in Astigmatism 353
10.15. The Dilemma of Relative Spectacle Magnification 354
10.16. Clinical Considerations in Anisometropia and Astigmatism 355
10.17. Indications of the Presence of Aniseikonia 356
10.18. Measurement of Image Size Differences 357
10.19. Estimating the Amount of Aniseikonia 360
10.20. Avoiding or Minimizing Induced Aniseikonia 361
10.21. Prescribing and Lens Design 362
10.22. The Use of Eikonic Lenses in Fit-Over Form 365
10.23. Frame Selection for Eikonic Lenses 368
10.24. Aniseikonia: Clinical Considerations in Anisometropia and Astigmatism 368
References 368
Questions 369
CHAPTER 11. Lenses for High Refractive Errors 372
11.1. Management of the Cataract Patient 373
11.2. Optical Consequences of Cataract Surgery 375
11.3. Predicting the Power of an Aphakic Lens 375
11.4. Problems with Aphakic Spectacles 376
11.5. Parameters of Aphakic Lenses 385
11.6. Aphakic Lens Design 386
11.7. Frames for Aphakic Lenses 390
11.8. The Unilateral Aphakic 390
11.9. Determining the Final Aphakic Prescription 393
11.10. The High Hyperope 394
11.11. Problems Caused by High Minus Lenses 395
11.12. Minimizing Edge Thickness 395
11.13. Minimizing Edge Reflections 397
11.14. Lenticular Lenses 399
11.15. Fresnel Press-on Lenses 400
References 401
Questions 401
CHAPTER 12. Optical Principles of Lenses for Low Vision 404
12.1. Methods of Providing Magnification 405
12.2. Afocal Telescopes 407
12.3. Headborne Telescopic Systems 411
12.4. Nonprescription Telescopes 411
12.5. Microscopic Lenses 412
12.6. Telescopic Lenses for Near Vision 418
12.7. Hand Magnifiers 420
12.8. Stand Magnifiers 423
12.9. The Paperweight Magnifier 425
References 426
Questions 426
CHAPTER 13. Optics of Contact Lenses 428
13.1. The Contact Lens as a Thick Lens 430
13.2. The Effective Power of a Contact Lens 432
13.3. Calibration of the Keratometer 433
13.4. The Contact Lens on the Eye 435
13.5. Over-refraction 438
13.6. Contact Lenses and Corneal Astigmatism 440
13.7. Fitting Steeper or Flatter than the Cornea 442
13.8. The Optics of Bifocal Contact Lenses 445
13.9. Residual Astigmatism and Its Correction 447
13.10. Magnification Effects of Contact Lenses 454
13.11. Accommodative Demand 456
13.12. Accommodative Convergence 456
13.13. Prismatic Effects 456
13.14. Prescribing Prism in a Contact Lens 459
13.15. Aberrations 459
13.16. Field of View 460
13.17. Aphakic Contact Lenses 461
13.18. The Radiuscope 463
References 464
Questions 464
Answers to Questions 467
Index 470

Produkt-Details

• Erscheint lt. Verlag: 22.10.2013
• Sprache: englisch
• Themenwelt: Medizin / Pharmazie ► Medizinische Fachgebiete ► Chirurgie
• Themenwelt: Naturwissenschaften ► Physik / Astronomie
• Themenwelt: Technik
• ISBN-10: 1-4831-9259-8 / 1483192598
• ISBN-13: 978-1-4831-9259-8 / 9781483192598