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Ophthalmic lenses made of plastic materials (e.g. CR 39 (ADC) or Polycarbonate) play an important role in the international marketplace and make a growing contribution to the number of spectacle lenses sold internationally. Worldwide about 40% of all spectacle lenses are made of plastic materials. The reason is their convenient combination of properties (optical homogeneity, low mass, low fragility). However the low abrasion resistance of their surface is disturbing. Therefore, in recent years great efforts were made to harden these lenses by coatings made of polysiloxane or similar materials. In most cases these coatings are made by a diving process or by spin-coating. In addition, the lenses often are vacuum-coated to minimise reflections. Hard coating will become common standard within a few years. The effect of hardening must be evaluated by a test method that meets practical use as closely as possible, and treats all of the complex abrasive processes that occur during practical use. Some methods are only applicable to plane surfaces while surfaces of ophthalmic lenses are spherical or torical. The shape of the surface should not have more influence on the test results than it has in normal wearing. The abrasion test developed in this project will give comparable figures for the abrasion resistance of different ophthalmic lenses. A text for a CEN-Standard is proposed which may be a basis for certification and performance requirements.

Additional information

Authors: DIEPES H, Transferzentrum Aalen, Institut für Augenoptik (DE)
Bibliographic Reference: EUR 14358 EN (1992) 101 pp., MF, ECU 8, blow-up copy ECU 10.50
Availability: (2)
Record Number: 199211171 / Last updated on: 1994-11-29
Original language: en
Available languages: en
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