Effect of polymerization method on the biostability of ocular prostheses

Abstract

The anophthalmic cavity environment can affect the ocular prosthesis surface due to the presence of tear enzymes, releasing potentially irritating substances and promoting surface roughness that compromises the clinical performance of the prosthesis. Therefore, enhancing biostability of ocular prosthesis would reduce the rate of complications and side effects. The aim of this study is to evaluate the biodegradation of ocular prosthesis made from acrylic resin (AR) that is polymerized by different heat cycles and methods, under simulated ophthalmic environment. The null hypothesis is that the different heat cycles and processing methods will not alter the biodegradation process of the AR used in ocular prostheses. Three hundred and eighty-five samples of N1 color AR will be distributed in 3 groups: N1 resin polymerized in water bath (NRWB), polymerized by microwave energy (NRME), or autopolymerized resin (ANR). In addition, different polymerization cycles will be analyzed and then the following analyses will be performed: analysis of tear composition and enzyme activity levels to formulate equivalent simulated human tear enzyme (SHTE) solution to be used in biodegradation assessment; analysis of biodegradation byproducts from ocular prosthesis AR aged in SHTE by using high performance liquid chromatography (HPLC) in combination with ultraviolet (UV) and mass spectrometry, scanning electron microscopy (SEM) for surface degradation analysis (×1000- and ×5000-magnification); analysis of AR composition with Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy; analysis of degree of vinyl group conversion using an FT-IR and; analysis of gel content of the AR. Quantitative data will be submitted to the test of adherence to the normal curve to determine if they do or do not originate from a normal distribution, and the appropriate statistical test will be applied. Qualitative data will be compared visually. (AU)