Glasses Despensing = تجهيز النظارات الطبية

Aseel O. Hamadeh, Nisreen M. Al-Aqqad

Description

The focus of this book is Glasses Despensing. It consists of Eleven Chapters. It’s discusses: (lenses Materials, Frame & Face Measurements, Optical Lenses, Measurements of Lens Curvature, Back Vertex Power & Distance, Prisms, Frame materials, Bifocal lenses, Absorptive lenses, Special Lens Designs and Fresnel prisms).

Sujets

• Sciences et techniques

Informations

• Publié par: Ottoman House Publishing
• Date de parution: 01 janvier 2013
• Nombre de lectures: 1
• EAN13: 9796500152684
• Langue: English
• Poids de l'ouvrage: 1 Mo

Extrait

 ﺰﻴﻬﺠﺗ  ﺔﻴﺒﻄﻟا تارﺎﻈﻨﻟا

Gl asses Despensi ng

Aseel O. Hamadeh Nisreen M. Al-Aqqad

2013

 ﺰﻴﻬﺠﺗ ﺔﻴﺒﻄﻟا تارﺎﻈﻨﻟا Gl asses Despensi ng

Contents ءاﺪﻫﻻا........................................................................................................1 Chapter One: lenses Materials.............................................................3 Glass lenses ................................................................................. 5 Plastic lenses ............................................................................... 8 Chapter Two: Frame & Face Measurements ...................................11 Frame Measurements: ............................................................... 13 Face measurements and frame selection................................... 17 Chapter Three: Optical Lenses ..........................................................21 Optical lenses ............................................................................ 23 Transposition............................................................................. 27 Designing a Lens to Change the Appearance of the Eye.......... 28 Chapter Four: Measurements of Lens Curvature ...........................31 Chapter Five: Back Vertex Power & Distance.................................40 Front & Back Vertex Power: .................................................... 41 Back vertex distance ................................................................. 43 Chapter Six: Prisms............................................................................46 Chpter Seven: Frame Materials.........................................................53 Chapter Eight: Bifocal & Multifocals Lenses...................................61 Bifocal lenses: ........................................................................... 63 Multifocal Lenses...................................................................... 69 Progressive Lenses.................................................................... 73 Anisometropic Problems with Bifocal Glasses......................... 77 Chapter Nine: Absorptive Lenses & Lens Coatings..........................83 Absorptive Lenses:.................................................................... 85 Lens Coatings............................................................................ 89 Chapter Ten: Special Lens Designs...................................................92 Chapter Eleven: Low Vision Aids ......................................................97 References .........................................................................................112

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Chapter One lenses Materials

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Introduction

Optical lenses are defined as transparent component made from optical materials and cured to converge or diverge rays come from an object.

Functions of lenses: 1.Correct refractive errors 2.Protect the eye from harmful rays 3.Protect the eye from occupational hazards

Materials of optical lenses: 1.Glass 2.Plastic

Glass lenses

The development of optical glass: Glass has two properties that make it especially suitable for optical uses. It is transparent to the visible spectrum, and its surface may be worked so that they are also transparent and nonscattering. The invention of spectacles (if we define spectacle as two lenses mounted in a frame and used for the correction of ametropia) apparently occurred late in the thirteen century. The early lenses were apparently used only for the correction of presbyopia. However, during this time, good quality homogeneous optical glass was not available.

The critical properties of optical glass: 1. The refractive index (n) velocity of light in vacuum N = velocity of light in an optical medium 2. Dispersion expressed by Abbe number (v) 3. Specific gravity: weight of material per unit volume

Types of glass lenses: The term“crown” and“flint” applied to optical glasses have lost their original meanings. -5-