Abstract
Purpose: :
To determine the extent an experimental multipurpose lens solution (MPS) containing a diblock copolymer of polyethylene oxide and polybutylene oxide can decrease silicone hydrogel (SiH) lens hydrophobicity by blocking the contact lens surface hydrophobic domains and whether or not the blocking of those domains influences the bulk lens total water content.
Methods: :
The extent of Sudan IV dye (dispersed in silicone oil) staining and adsorption over time was used to gauge the surface and bulk effects of the test MPS on the hydrophobic domains of four types of silicone hydrogel lenses (Balafilcon, Lotrafilcon, Senofilcon, Comifilcon). Additionally, gravimetric analysis was used to monitor the contact lens water content over 14 days of simulated daily wear conditions where lenses were soaked in artificial tear solution for 12 hours and then multipurpose solution for 12 hours of every 24 hours.
Results: :
The test MPS significantly blocked the sorption of Sudan IV to all four lens types as compared to control lenses. The extent of blocking was dependent on the lens type and the time of exposure; however, in general the extent of blockage was Balafilcon>Lotrafilcon> Comfilcon, Senofilcon. Longer periods of exposure to the Sudan IV indicated that the test MPS blocked the hydrophobic domains by over 50% for all the tested lens types. There was no statistically significant change in lens water content at the end of the 14 day test period for any of the lenses regardless of the soaking conditions and exposure times.
Conclusions: :
The experimental multipurpose lens solution (MPS) significantly decreased the binding of Sudan IV to both surface and bulk hydrophobic domains in all lens types tested. This effect is believed to be important in improving the wettability, lubrication and lipid prevention properties of the novel block copolymer.
Keywords: contact lens • lipids