Neutral red assay of the cytotoxicity of fluorocarbon-coated polymethyl methacrylate intraocular lenses in vitro

Polymethylmethacrylate (PMMA) intraocular lenses (IOLs) were coated with Te flon AF, an amorphous, transparent Teflon, to render them highly hydrophobi c, Teflon-coated PMMA IOLs were immersed in culture medium for 30 days at 3 7 degrees C. Four concentrations of the IOL leachables, 2 concentrations of a tor;ic control (phenol), and complete liquid culture medium (nontoxic co ntrol) were incubated for 24 h in a 96-well plate containing confluent L-92 9 fibroblasts. The cytotoxic effect of each solution on the fibroblasts was quantitatively assessed by measuring the uptake of neutral red by the viab le cells. After the extraction of the neutral red using 1% acetic acid-50% ethanol, the optical densities were measured with a microplate reader at 55 0 nm, Scanning electron microscopy (SEM) and X-ray photoelectron spectrosco py (XPS) were used to analyze the surfaces of the IOLs. Only the optical de nsities in the wells containing fibroblasts that had been in contact with t he phenol solutions were significantly lower than those in the wells incuba ted with the nontoxic control solution (p < 0.01), There were no signs of s urface alteration by SEM, apart from some crystals on the IOLs, The crystal s were composed of Na and Cl, as demonstrated by XPS, Aqueous extractables from the Teflon-coated IOLs produced no cytotoxic effects in the neutral re d assay used. (C) 1999 John Wiley & Sons, Inc.