Safety of silicone oils as intraocular medical device: An in vitro cytotoxicity study

This study aimed to assess the cytotoxic e!ect of low molecular weight components (LMWC) and conventional silicone oils (SOs) 1000 cSt with di!erent degree of puri"cation (raw, intermediate, and puri"ed) using in vitro cytotoxicity tests. Direct contact cytotoxicity tests were performed in BALB 3T3 and human retinal pigment epithelial cells (ARPE-19) using quantitative and qualitative evaluation according to the ISO 10993-5 (2009) standards. Conventional SOs 1000 cSt in form of raw, intermediate (intermediate product obtained during distillation process), and puri"ed SO ("nal product after distillation) and a concentrate of LMWC (including siloxane chains with molecular weight up to 1557 g/mol) were directly applied to 100% of cell layer area for 24 h. Cell viability was quanti"ed using 3-(4,5-dimethylthiazole-2-yl)-2,5–28 diphenyltetrazolium bromide (MTT) and neutral red uptake assays in ARPE-19 and BALB3T3, respectively. All tested samples, including the concentrate of LMWC, resulted to be not cytotoxic according to ISO 10993-5 in both qualitative and quantitative evaluations. However, the cellular viability was signi"cantly higher in the intermediate and puri"ed SO compared with the raw SO in ARPE-19 cells. No reduction in cell viability was detected by LMWC. The absence of cytotoxicity was observed for all tested samples in both BALB3T3 and ARPE-19 after 24 h of application. A direct cytotoxic e!ect is not likely to be involved in the potential complications related to SO and LMWC. Long-term potential adverse e!ects of SO could be related to the raw material and to di!erent concentrations of LMWC.