Abstract
Abstract: :
Purpose: To determine the preservative uptake and release profiles of PHMB from PHMB–containing contact lens care products by two types of commercial silicone hydrogel soft contact lenses. Methods: Two commercial brands of silicon hydrogel soft contact lenses (Focus® NIGHT & DAYTM and PureVisionTM) were soaked in PHMB–preserved soft contact lens care solutions at ambient temperature for 1 or 7 days, and the lens PHMB uptake was measured via HPLC analysis of the soak solutions. Preservative release was measured by soaking these lenses in phosphate buffered saline (PBS) at 35 °C for 1 or 4 days followed by HPLC analysis of the PBS. Results: Based on these studies, after the 1–day soak time in the tested lens care solutions, both lens types took up considerably less PHMB from SOLOcareTM, SOLOcareTM PLUS and AQuifyTM MPS solutions than they took up from the ReNu MultiPlus® solution. Regardless of soak time or type of solution, PureVisionTM soft contact lenses took up considerably more PHMB than Focus® NIGHT & DAYTM lenses, with little to no PHMB uptake by the Focus® NIGHT & DAYTM lenses in most cases. The preservative uptake was at least partially reversible, with the amount of the PHMB released in the PBS soak for the Focus® NIGHT & DAYTM lenses equivalent to or less than that for the PureVisionTM lenses in most cases. Conclusions: Although all of the tested contact lens care products contain 1 ppm PHMB, the uptake of this preservative by silicone hydrogel lenses appears to also be dependent on the overall solution formulation matrix. These results suggest that not all PHMB–containing contact lens care solutions are equal. Focus® NIGHT & DAYTM silicon hydrogel soft contact lenses also appear to have a much lower propensity to take up PHMB from contact lens care solutions than PureVisionTM lenses.