Additional Information
Book Details
Abstract
The Contact Lens Manual continues to meet the needs of a new generation of optometrists, dispensing opticians, contact lens practitioners and students who require clear and reliable information for fitting a complete range of contact lenses.
The fourth edition of this best-selling classic, now in full colour throughout, provides the most up-to-date guidance in all aspects of today’s lenses in a practical and easy to use manual. Featuring new developments in lens types, care regimes and current practices, this manual offers a complete package to help readers expand their lens knowledge, improve fitting and optimise patient care.
- The authors use a down-to-earth practical approach to distil years of experience into one handy volume.
- A bullet point style makes the information easily accessible.
- Key information is presented so it can be quickly located.
- Practical tips, clinical pearls, helpful advice, and warnings are presented in boxes so readers can see at a glance what to do.
- Features updates to all chapters and lens types with a wealth of new information on silicone hydrogels, toric soft lenses, rigid gas-permeable fitting and patient after care.
- Presents a new chapter on dry eyes with expert guidance on treatment and practical management advice.
- Includes an expanded illustration programme and page design with full colour throughout including colour-coded sections and boxes to highlight key information for easier learning.
Table of Contents
| Section Title | Page | Action | Price |
|---|---|---|---|
| Front cover | cover | ||
| Half Tital page | i | ||
| CD-Rom Licence Agreement | ii | ||
| The Contact Lens Manual | iii | ||
| Copyright | iv | ||
| Table of Contents | v | ||
| Preface to the fourth edition | xi | ||
| Preface to the first edition | xii | ||
| Common abbreviations in contact lens practice | xiii | ||
| ONE Preliminaries | 1 | ||
| 1 Background | 1 | ||
| 1.1 Applied anatomy | 1 | ||
| 1.1.1 The cornea | 1 | ||
| Epithelium | 1 | ||
| Bowman’s membrane | 2 | ||
| Stroma | 2 | ||
| Descemet’s membrane | 2 | ||
| Endothelium | 2 | ||
| Corneal sensitivity | 2 | ||
| 1.1.2 The conjunctiva | 2 | ||
| 1.1.3 The eyelids | 3 | ||
| 1.1.4 The tear film | 3 | ||
| Functions | 3 | ||
| Composition | 3 | ||
| 1.2 Applied physiology | 4 | ||
| 1.2.1 Corneal metabolism | 4 | ||
| 1.2.2 Oxygen consumption | 4 | ||
| 1.2.3 Corneal temperature | 5 | ||
| 1.2.4 Stromal acidosis | 5 | ||
| 1.2.5 Tear osmolarity | 5 | ||
| 1.2.6 Tissue fragility | 5 | ||
| 1.2.7 Cell apoptosis | 6 | ||
| 1.2.8 Corneal sensitivity | 6 | ||
| 1.2.9 Closed eyelid conditions during sleep | 6 | ||
| 1.3 Physical properties of materials | 6 | ||
| 1.3.1 Oxygen permeability, oxygen transmissibility and equivalent oxygen percentage | 6 | ||
| Oxygen permeability | 6 | ||
| Oxygen transmissibility | 7 | ||
| Surface effects | 7 | ||
| Edge effect | 8 | ||
| Boundary effects | 8 | ||
| Equivalent oxygen percentage | 8 | ||
| Oxygen flux | 8 | ||
| 1.3.2 Water content and water uptake | 10 | ||
| Water balance ratio | 10 | ||
| 1.3.3 Wettability | 10 | ||
| 1.4 Manufacture of lenses | 12 | ||
| Regulation | 12 | ||
| 1.4.1 Rigid lens manufacture | 12 | ||
| Polishing | 12 | ||
| 1.4.2 Soft lens manufacture | 12 | ||
| 1.4.3 Toric lens manufacture | 13 | ||
| Soft lenses | 13 | ||
| Rigid gas-permeable lenses | 13 | ||
| References | 14 | ||
| 2 Instrumentation | 15 | ||
| 2.1 Slit lamp | 15 | ||
| 2.1.1 Instrument controls and focus | 15 | ||
| 2.1.2 Methods of illumination | 16 | ||
| Direct methods | 16 | ||
| Indirect methods | 17 | ||
| 2.1.3 Recommended slit lamp routine | 17 | ||
| 2.2 Keratometers and autokeratometers | 20 | ||
| 2.2.1 Types of keratometer (ophthalmometer) | 20 | ||
| Variable doubling | 21 | ||
| Fixed doubling | 21 | ||
| 2.2.2 Focusing the eyepiece | 22 | ||
| 2.2.3 Taking a measurement | 22 | ||
| 2.2.4 Extending the range | 23 | ||
| 2.2.5 Topographical keratometer | 23 | ||
| 2.2.6 Autokeratometers | 23 | ||
| 2.3 Corneal topographers | 23 | ||
| Placido based | 24 | ||
| Advantages | 24 | ||
| Disadvantages | 24 | ||
| Slit scan topography | 25 | ||
| Advantage | 25 | ||
| Disadvantages | 25 | ||
| Scheimpflug based topography | 25 | ||
| 2.3.1 Analysis of corneal topography (Oculus Keratograph) | 25 | ||
| Contour maps | 25 | ||
| Absolute maps | 26 | ||
| Axial maps | 27 | ||
| Tangential maps | 27 | ||
| Topographical shapes | 28 | ||
| Shape factor (SF) | 29 | ||
| Elevation maps | 29 | ||
| Difference maps | 29 | ||
| Fourier analysis | 30 | ||
| Zernicke analysis | 30 | ||
| Applications | 31 | ||
| Aberrometry | 31 | ||
| 2.4 Anterior segment photography | 31 | ||
| Advantages of image capture | 33 | ||
| Contrast sensitivity (CS) | 33 | ||
| 2.5 Specialist instruments for higher magnification | 33 | ||
| Specular microscope | 33 | ||
| Confocal microscope | 33 | ||
| 2.6 Other instruments | 34 | ||
| Burton lamp | 34 | ||
| Pachymeters | 34 | ||
| Placido disc | 34 | ||
| Thermography | 35 | ||
| References | 35 | ||
| Further reading | 35 | ||
| 3 Record keeping | 37 | ||
| 3.1 Legal implications | 37 | ||
| Informed consent | 37 | ||
| Record keeping | 38 | ||
| Telephone conversations | 39 | ||
| Complaints | 39 | ||
| Patient access to records | 39 | ||
| Specification and replication | 39 | ||
| Responsibility | 40 | ||
| Out-of-hours cover | 40 | ||
| Committee on the Safety of Medicines | 41 | ||
| Product liability | 41 | ||
| Medical Device Directive | 41 | ||
| 3.2 Record cards | 42 | ||
| 3.3 Clinical grading | 42 | ||
| Published grading scales | 42 | ||
| The CCLRU grading scale | 42 | ||
| The Efron grading scale for contact lens complications | 43 | ||
| The Institute of Optometry grading scale | 43 | ||
| 3.4 Computerization of patient records | 44 | ||
| Data Protection Act | 44 | ||
| References | 44 | ||
| Further reading | 45 | ||
| 4 Consulting room procedures and equipment | 47 | ||
| 4.1 Hygienic procedures to avoid cross-infection | 47 | ||
| Hand washing between patients | 47 | ||
| Decontamination and disinfection of trial lenses | 47 | ||
| Disinfection of instrumentation | 47 | ||
| Temporary lens containers | 48 | ||
| 4.2 Solutions and drugs | 48 | ||
| Water | 48 | ||
| Saline (0.9% sodium chloride BP) | 48 | ||
| Proprietary solutions | 48 | ||
| Staining agents | 48 | ||
| Fluorescein sodium BP | 48 | ||
| High molecular weight fluorescein (e.g. Fluorexon) | 49 | ||
| Rose bengal 1% | 49 | ||
| Lissamine green | 49 | ||
| Alcian blue | 50 | ||
| Topical anaesthetics | 50 | ||
| Benoxinate 0.4%; amethocaine 0.5% and 1.0% | 50 | ||
| Antimicrobial agents | 50 | ||
| Chloramphenicol BP 0.5% | 50 | ||
| Fucithalmic 1% | 50 | ||
| Brolene (0.1% propamidine isetionate) | 50 | ||
| Other drugs | 50 | ||
| Sodium cromoglycate 2% (e.g. Opticrom, Broleze, Vividrin) | 50 | ||
| Lodoxamide (e.g. Alomide) | 51 | ||
| Adrenalin 1% | 51 | ||
| Sodium bicarbonate 2% | 51 | ||
| 4.3 Decontamination and disinfection of trial lenses | 51 | ||
| Decontamination and disinfection of rigid gas-permeable and PMMA lenses | 52 | ||
| Soft lenses | 53 | ||
| In case of accident | 53 | ||
| 4.4 Other procedures | 53 | ||
| 4.4.1 Professional cleaning and rejuvenation | 53 | ||
| Rigid lenses | 53 | ||
| Soft lenses | 54 | ||
| 4.4.2 Lens verification | 54 | ||
| 4.4.3 Ancillary items | 54 | ||
| 4.5 Insertion and removal by the practitioner | 54 | ||
| 4.5.1 Rigid gas-permeable and PMMA lenses | 55 | ||
| TWO Rigid gas-permeable lens fitting | 111 | ||
| 8 Principles of rigid lens design | 111 | ||
| 8.1 Basic principles of rigid lens design | 111 | ||
| 8.2 Forces controlling design | 111 | ||
| 8.2.1 Centre of gravity | 111 | ||
| 8.2.2 Frictional forces | 112 | ||
| 8.2.3 Capillary attraction | 113 | ||
| 8.2.4 Specific gravity | 113 | ||
| 8.2.5 Thickness and lenticulation | 113 | ||
| 8.2.6 Refractive index of materials | 115 | ||
| 8.2.7 Edge shape | 115 | ||
| 8.3 Concept of edge lift | 116 | ||
| Band width method | 118 | ||
| Step-by-step method | 118 | ||
| 8.3.1 Concept of edge clearance | 118 | ||
| 8.4 Tear layer thickness | 119 | ||
| Typical values | 119 | ||
| 8.5 Lid attachment lenses | 120 | ||
| Advantages | 120 | ||
| THREE Hydrogel and silicone hydrogel fitting | 187 | ||
| 15 Soft lens fitting and design | 187 | ||
| 15.1 Fitting considerations | 187 | ||
| 15.1.1 Sagittal height and corneal measurement | 187 | ||
| Large corneas with steep radii | 187 | ||
| Small corneas with flat radii | 187 | ||
| 15.1.2 Dynamic assessment of fitting | 188 | ||
| The ‘push-up’ test | 188 | ||
| 15.1.3 Design factors | 188 | ||
| 15.2 Corneal diameter lenses | 189 | ||
| Indications | 189 | ||
| Contraindications | 189 | ||
| Fitting | 189 | ||
| Radius | 189 | ||
| Total diameter | 190 | ||
| Power | 190 | ||
| Fitting appearance | 190 | ||
| Clinical equivalents | 191 | ||
| To improve a loose fitting | 192 | ||
| To improve a tight fitting | 192 | ||
| 15.2.1 Example of a corneal diameter lens | 192 | ||
| Lunelle ES 70 (CooperVision) | 192 | ||
| Material properties | 192 | ||
| Lens geometry | 192 | ||
| Parameters available | 192 | ||
| Fitting technique | 192 | ||
| Typical lens specification | 193 | ||
| Related lenses | 193 | ||
| 15.3 Semi-scleral lenses | 193 | ||
| Indications | 193 | ||
| Contraindications | 193 | ||
| Fitting | 193 | ||
| Radius | 193 | ||
| Total diameter | 194 | ||
| Power | 194 | ||
| Fitting appearance and lens movement | 194 | ||
| Clinical equivalents and altering the fitting | 195 | ||
| To improve a loose fitting | 196 | ||
| To improve a tight fitting | 196 | ||
| 15.3.1 Examples of semi-scleral lenses | 196 | ||
| Durasoft 3 Lite Tint (CIBAVision) | 196 | ||
| Material properties | 196 | ||
| Lens geometry | 197 | ||
| FOUR Complex lenses | 253 | ||
| 22 Toric rigid lenses | 253 | ||
| 22.1 Residual and induced astigmatism | 253 | ||
| Residual astigmatism | 253 | ||
| Induced astigmatism | 254 | ||
| Ocular refraction | 254 | ||
| 22.2 Patient selection | 254 | ||
| 22.2.1 Indications and contraindications | 254 | ||
| Indications | 254 | ||
| To improve the physical fit | 254 | ||
| To give optimum visual acuity | 255 | ||
| Contraindications | 255 | ||
| 22.3 Lens designs | 255 | ||
| 22.3.1 Non-toric lens forms | 255 | ||
| Small spherical lenses | 255 | ||
| Aspheric lenses | 255 | ||
| 22.3.2 Toric lenses | 255 | ||
| Back surface toric | 255 | ||
| Bitoric | 256 | ||
| Front surface toric | 256 | ||
| Toric periphery | 256 | ||
| 22.4 Methods of stabilization | 256 | ||
| Prism ballast | 256 | ||
| Truncation | 256 | ||
| 22.5 Fitting back surface torics | 256 | ||
| 22.5.1 Toric fitting set | 256 | ||
| 22.5.2 Spherical fitting set | 257 | ||
| 22.5.3 Fitting by calculation | 257 | ||
| 22.6 Fitting bitorics | 259 | ||
| 22.7 Compromise back surface torics | 259 | ||
| 22.8 Fitting front surface torics | 260 | ||
| Method 1 | 260 | ||
| Method 2 | 261 | ||
| 22.9 Fitting toric peripheries | 261 | ||
| 22.10 Computers in toric lens fitting | 262 | ||
| References | 262 | ||
| 23 Toric soft lenses | 263 | ||
| 23.1 Patient selection | 263 | ||
| Indications | 263 | ||
| Contraindications | 263 | ||
| 23.2 Stabilization | 264 | ||
| 23.2.1 Influences on lens behaviour | 264 | ||
| 23.2.2 Methods of stabilization | 264 | ||
| Prism ballast | 264 | ||
| FIVE Management | 305 | ||
| 26 Care systems | 305 | ||
| 26.1 Components of solutions | 305 | ||
| Buffers | 305 | ||
| Preservatives | 305 | ||
| Polyquats | 305 | ||
| Benzalkonium chloride (BAK) | 306 | ||
| Chlorhexidine digluconate (CHX) | 306 | ||
| Thiomersal | 306 | ||
| Aldox | 306 | ||
| Water-soluble cationics | 306 | ||
| Phenylmercuric nitrate and chlorbutol | 307 | ||
| Quaternary ammonias | 307 | ||
| Sorbic acid | 307 | ||
| Polyvinyl alcohol | 307 | ||
| Tonicity agents (invariably sodium or potassium chloride) | 307 | ||
| Viscosity agents (e.g. hydroxyethylcellulose) | 307 | ||
| Wetting agents (e.g. polyvinyl alcohol, polysorbate 80) | 307 | ||
| Lubricating agents (e.g. hydroxypropyl methylcellulose (HPMC), Lubricare) | 307 | ||
| Chelating agents (e.g. ethylenediamine tetraacetic acid (EDTA) known as sodium edetate) | 307 | ||
| Sequestering agents (e.g. citrate, hydranate) | 307 | ||
| Surfactants (e.g. poloxamine, miranol) | 308 | ||
| Wetting and cleaning agents (e.g. TearGlyde) | 308 | ||
| 26.1.2 Disinfection standards | 308 | ||
| Stand alone test | 309 | ||
| Regimen test | 309 | ||
| 26.2 Solution for soft lenses | 309 | ||
| 26.3 Disinfection | 309 | ||
| 26.3.1 Chemical disinfection | 309 | ||
| Multipurpose solutions | 309 | ||
| Oxidative systems | 310 | ||
| Hydrogen peroxide (H2O2) | 310 | ||
| Advantages of hydrogen peroxide | 311 | ||
| Disadvantages of hydrogen peroxide | 311 | ||
| Chlorine systems | 312 | ||
| 26.3.2 Heat disinfection | 312 | ||
| Microwave | 312 | ||
| Saline | 312 | ||
| Tap water | 313 | ||
| 26.3.3 Cleaning solutions | 313 | ||
| Other cleaning methods | 314 | ||
| 26.3.4 Case hygiene | 314 | ||
| 26.3.5 Rewetting solutions | 314 | ||
| 26.3.6 Periodic cleaners | 314 | ||
| Enzyme tablets | 314 | ||
| 26.3.7 Contact lens case | 315 | ||
| 26.4 Solutions for rigid gas-permeable lenses | 315 | ||
| 26.4.1 Wetting solutions | 315 | ||
| 26.4.2 Soaking solutions | 315 | ||
| 26.4.3 Cleaning solutions | 315 | ||
| 26.4.4 Multipurpose solutions | 316 | ||
| 26.4.5 Rewetting solutions (comfort drops) | 317 | ||
| 26.4.6 Enzyme tablets | 317 | ||
| 26.4.7 Tap water | 317 | ||
| 26.4.8 Contact lens case | 318 | ||
| 26.5 Compliance and product misuse | 318 | ||
| References | 318 | ||
| 27 Lens collection and patient instruction | 319 | ||
| 27.1 Lens collection | 319 | ||
| Insertion of lenses | 319 | ||
| Assessment of vision | 319 | ||
| Assessment of fitting | 319 | ||
| 27.2 Insertion and removal | 319 | ||
| 27.2.1 Rigid lenses | 320 | ||
| SIX Children and therapeutic lenses | 367 | ||
| 31 Contact lenses and children | 367 | ||
| 31.1 Management | 367 | ||
| Parental management | 367 | ||
| 31.1.2 Child management | 367 | ||
| 31.1.3 Insertion and removal | 367 | ||
| Insertion | 367 | ||
| Removal | 368 | ||
| 31.1.4 Anaesthetics | 368 | ||
| 31.1.5 Hypnosis | 368 | ||
| 31.2 Instrumentation | 369 | ||
| 31.3 Non-therapeutic fitting | 369 | ||
| 31.4 Refractive applications | 370 | ||
| 31.4.1 Myopia | 370 | ||
| Myopia control | 370 | ||
| Orthokeratology | 370 | ||
| 31.4.2 Hypermetropia | 370 | ||
| 31.4.3 Anisometropia | 370 | ||
| 31.4.4 Amblyopic occlusion | 371 | ||
| 31.5 Therapeutic applications | 371 | ||
| 31.5.1 Aphakia | 371 | ||
| 31.5.2 Albinism | 371 | ||
| 31.5.3 Aniridia and iris coloboma | 372 | ||
| 31.5.4 Microphthalmos | 372 | ||
| 31.5.5 Marfan’s syndrome | 372 | ||
| References | 372 | ||
| 32 Therapeutic and complex lens designs | 375 | ||
| Therapeutic fitting with rigid gas-permeable and soft lenses | 375 | ||
| 32.1 High myopia and hypermetropia | 376 | ||
| 32.1.1 Rigid gas-permeable lenses | 376 | ||
| 32.1.2 Hydrogel lenses | 376 | ||
| 32.1.3 Silicone hydrogel lenses | 376 | ||
| 32.2 Keratoconus | 376 | ||
| 32.2.1 Rigid lenses | 377 | ||
| Spherical lenses to give two-point touch | 377 | ||
| Spherical lenses to give three-point touch | 378 | ||
| Apical clearance lenses | 379 | ||
| Spherical lenses to fit the corneal periphery | 379 | ||
| Offset and aspheric lenses | 379 | ||
| Elliptical ‘K’ (Persecon keratoconus) | 380 | ||
| Aspheric periphery lenses | 380 | ||
| Quasar K | 380 | ||
| Acuity lenses | 380 | ||
| Rose K lens | 381 | ||
| Rose K2 | 381 | ||
| Profile design | 382 | ||
| ‘CLEK’ standardized fitting set | 382 | ||
| Corneoscleral lenses | 382 | ||
| So2Clear | 382 | ||
| Insertion | 383 | ||
| Removal | 383 | ||
| Fitting | 383 | ||
| Central fitting | 383 | ||
| Peripheral curve | 383 | ||
| Total diameter | 383 | ||
| Fluorescein instillation | 384 | ||
| Keratoconus | 384 | ||
| Ordering | 384 | ||
| 32.2.2 Soft lenses | 385 | ||
| Conical soft lenses | 385 | ||
| Spherical soft lenses | 385 | ||
| Hybrid lenses | 385 | ||
| SoftPerm (CIBAVision) | 386 | ||
| Synergeyes KC (Paragon) | 386 | ||
| Piggy-back systems | 386 | ||
| Scleral soft lenses | 386 | ||
| 32.3 Aphakia | 386 | ||
| 32.3.1 Rigid lenses | 387 | ||
| Corneal lens fitting | 387 | ||
| Corneoscleral lenses | 388 | ||
| Apex lens | 388 | ||
| Dyna intra-limbal | 388 | ||
| 32.3.2 Soft lenses | 389 | ||
| Hydrogels | 389 | ||
| Continuous wear | 389 | ||
| Silicone hydrogels | 389 | ||
| 32.4 Corneal grafts (keratoplasty) | 390 | ||
| 32.4.1 Rigid lenses | 390 | ||
| Reverse geometry lenses | 390 | ||
| Rose K post graft keratoconus lens | 390 | ||
| 32.4.2 Soft lenses | 390 | ||
| 32.5 Corneal irregularity | 391 | ||
| 32.5.1 Rigid gas-permeable lenses | 391 | ||
| 32.5.2 Soft lenses | 391 | ||
| 32.6 Albinos | 391 | ||
| 32.7 Radial keratotomy and photo- refractive keratectomy | 391 | ||
| 32.8 Combination lenses | 392 | ||
| 32.8.1 ‘Piggy-back’ lenses | 392 | ||
| 32.8.2 Rigid centre with soft periphery | 392 | ||
| Softperm | 392 | ||
| SynergEyes® | 393 | ||
| 32.9 Silicone rubber lenses | 393 | ||
| Advantages | 393 | ||
| Disadvantages | 394 | ||
| 32.10 Bandage lenses | 394 | ||
| 32.10.1 Soft lenses | 394 | ||
| General considerations | 394 | ||
| 32.10.2 Limbal diameter rigid gas permeable lenses | 395 | ||
| 32.11 Additional therapeutic uses | 395 | ||
| Drug-release lenses | 395 | ||
| Low-vision aid | 395 | ||
| Veterinary lenses | 395 | ||
| References | 395 | ||
| Appendix 1 | 397 | ||
| Appendix 2 Useful contact lens internet sites | 401 | ||
| Journals | 401 | ||
| Teaching resources | 402 | ||
| Professional | 403 | ||
| General interest | 403 | ||
| Technology | 403 | ||
| Dry eye | 404 | ||
| Investigative techniques | 404 | ||
| Ophthalmology | 404 | ||
| Glossary | 405 | ||
| Glossary of contact lens-related terms | 405 | ||
| Index | 417 |