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Introduction Introduction Materials and treatments are the basic constituents of ophthalmic lenses: they provide optical correction and comfortable vision. More precisely, the materials create the optical function of the lens in combination with the surface geometry and treatments provide visual comfort by adding multiple properties to the lenses. Together their purpose is to allow the wearer to forget his/her corrective lenses. In just a few decades, materials and treatments have seen profound changes: plastics have replaced glass lenses, the use of scratch-resistant and anti-reflective treatments has become commonplace and numerous materials and treatments have appeared. Ophthalmic lenses have a complex structure: they result from the interlayering of a material and a series of treatments, each of which is a response to a specific need: reduced thickness, light weight, transparency, durability, strength, protection, aesthetics, etc. An ophthalmic lens can have up to twenty of these thin layers deposited on the front and rear surfaces (figure 1). Materials and treatments form an indivisible whole: if the material has the essential function of providing optical correction, it also has the purpose of being the carrier for the various treatments. The study of materials cannot be separated from that of treatments and, conversely, treatments cannot be studied independently of the materials with which they are as- sociated. That is the reason why “Materials and Treatments” are dealt with jointly in a single Ophthalmic Optics File. & TREATMENTS In order to give a structured summary, all the concepts presented in this file are first of all presented from the point of view of the needs of the lens wearer and technical elements are then considered as responses to these needs. That is why this file contains four sections : I) Thickness and weight II) Transparency and durability III) Strength and protection IV) Aesthetics and fashion In each of these section the needs and expectations of the wearer are described first of all and the design and manufac- MATERIALS turing techniques used are presented afterwards. This volume “Materials and Treatments” in the collection “Ophthalmic Optics Files” aims to present in summary form the essential concepts used in the composition and internal design of lenses. It will take you on a fascinating journey through the very heart of ophthalmic lenses. Anti-smudge Anti-reflection Anti-scratch Flexible layer © Essilor International Tinting (optional) Material Figure 1 : Structure of an ophthalmic lens. 5 Copyright © 2010 ESSILOR ACADEMY EUROPE, 13 rue Moreau, 75012 Paris, France - All rights reserved – Do not copy or distribute.
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