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Supplement Supplement The principles of lens manufacturing Ophthalmic lenses are manufactured in two ways (see figure 12): - “mass” production : for the large volume production of the most commonly required finished lenses (spherical and aspheric single vision) and for the production of “semi-finished” lenses, thick lenses whose front face is finished and whose rear face will be surfaced as required; - “prescription” manufacture: • either from a semi-finished lens: the operation consists of surfacing the rear face according to the patient’s optical correction and subjecting the lens to various surface treatments (tinting, scratch resistance, anti-reflection, anti-smudge, etc.) • or by direct surfacing of the two lens faces or direct polymerization, followed by various surface treatment operations. Mass production is carried out on a large scale in manufacturing plants (approximately two thirds of lenses); “prescription” manufacturing is effected piece by piece in finishing laboratories (one third of lenses). The number of possible combinations – of optical corrections, materials and treatments – is very high (usually estimated at more than five & TREATMENTS billion)! It makes the organisation of lens manufacturing very complicated. One of the great skills of the ophthalmic optics industry is the management of a highly complex production-logistics chain, which makes it possible to manufacture “custom” lenses on a large scale (approximately one billion lenses are produced worldwide every year). FACTORY FINISHED SEMI-FINISHED FACTORY (TINTING) ANTI-SCRATCH ANTI-REFLECTION MATERIALS STOCK SURFACING LAB (TINTING) ANTI-SCRATCH ANTI-REFLECTION FINISHING FINISHING EDGING © Essilor International ECP ECP MOUNTING Figure 12: General lens manufacturing principles. 15 Copyright © 2010 ESSILOR ACADEMY EUROPE, 13 rue Moreau, 75012 Paris, France - All rights reserved – Do not copy or distribute.