Post-operative complications of poly (methyl methacrylate) employed in intraocular lenses

Ghatora, Baljit [Speaker] (2012) Post-operative complications of poly (methyl methacrylate) employed in intraocular lenses. In: Recent appointees in Materials Science; 05 - 07 Sep 2012, Glasgow, U.K..


Poly (methyl methacrylate) (PMMA) is one of the most biocompatible biomaterials used in the fabrication of medical devices. The physical characteristics and mechanical strength enables PMMA to be used in applications such as dentures and bone cement while the high refractive index and excellent light transparency make it ideal for use in contact lenses and ocular implants, and in particular IOLs. Since the first IOL implantation performed by Harold Ridley in November 1949, PMMA still remains the gold standard material that current intraocular lenses are compared against. However one of recently-identified postoperative complications that leads to the failure of implanted intraocular lenses is termed as calcification, whereby calcium containing deposits build up on the surface of the IOL. Within literature there has been substantial studies carried out upon explanted opacified silicone and hydrophilic based IOLs to assess for calcium containing deposits. However the novelty of this in vitro study is that, to the authors’ knowledge, it is the first of its kind studying the calcification of medical grade PMMA within a simulated aqueous humour solution (SAHS). Medical grade PMMA discs sterilised using gamma irradiation or ethylene oxide gas were incubated in SAHS at 35oC and routinely removed for analysis to investigate any deposition. The mass uptake after immersion in the SAHS was studied using gravimetric analysis, and the data was subsequently analysed in diffusion studies. After immersion any surface deposits were analysed using scanning electron microscopy (SEM) coupled with Energy Dispersive X-ray analysis (EDXA) indicated that surface deposition was occurring as soon as 24 hours after incubation. Subsequent to analysis of the deposits it was proposed that surface modification of the IOL surface would hinder calcium containing deposits. The surface fluorinated IOLs immersed within the SAHS were removed over periods of time and tested for the presence of deposits, where SEM; EDXA exhibited promising results in employing the surface modification.

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