Plastics on the eye - plastics in the eye. Humanoptic materials

Background: Materials of identical or similiar chemical classes are used for contact optics as well as for implantable intraocular devices. All of them derive from the chemistry of industrial product developments. Patients and methods: Materials used in and on the eye should behave indifferent. They should not provoke any reaction in the eye and not themselves be alterated by the biological surroundings. For materials used in the eye an especially high purity of the polymers utilized as well as a long term light stability is to be demanded. Optical properties like transparency have to be stable over extended time periods under normal light influence. The long time stability of UV-absorbing additives in the materials used has to be verified. Results: All materials used for IOL's - with the exception of the homopolymer of methylmethacrylate - consit of polymer mixtures forming socalled interpenetrating networks which appear as an uniform material. For the manufacturing of intraocular lense materials standardized or unanimous producer prescriptions are not existing. Based on the different polymer formulations different aging and fatigue peoperties are the outcome. In addition only inadequate knowledge about the long term light stability of the incorporated UV blockers is submitted. Conclusions: Polymeric materials used for IOL's should be subjected in addition to the test methods listed in EN-ISO 11979/5 to chemical, polymer-analytic and mechanical substance examinations. As a standard in such examinations a polymethylmethacrylate, free of methylacrylate is proposed. Examinations of each lot should be compulsory. Identification of all ingredients of the intraocular materials should be prescribed and labeled in line with the revelations of common medical drugs prescriptions. The relevations commit the medical doctor to inform his patient about possible side effects of the intraocular implants.