Abstract
Purpose:
We investigated the effect of replenishing the artificial tear fluid (ATF) over the study period on the lipid penetration profile into silicone hydrogel lenses.
Methods:
We compared the lipid biofouling penetration profiles of five contact lens materials after 12 hours of exposure to static ATF daily wear conditions and daily wear conditions where the ATF was replaced hourly using fluorescently-labeled phosphatidylcholine and cholesterol. Lipid penetration differences between the central 6 mm and the peripheral edges of the lenses were imaged with confocal microscopy.
Results:
The non-static method allowed for more adsorption and penetration of both phosphatidylcholine and cholesterol into all lenses types tested (p=0.0001). There was approximately a 2-fold increase in the amount of cholesterol found in all the lenses with the non-static method as compared to the static. While there was also an increase in the amount of PC within all lenses with the non-static method compared to the static method is was not as significant as the cholesterol. The non-static method also showed more significant differences between the lipid penetration profiles for the lens types compared to the static method. The non-static method showed more surface penetration of PC in the periphery of the lens as compared to the center for Acuvue Oasys, Biofinity and PureVision 2 than Air Optix and AirOptix Aqua which was not seen with the static method. However, the penetration profile for cholesterol did not change significantly between the non-static and the static methods for any of the lenses tested.
Conclusions:
The non-static method provided better differential analysis of lipid penetration into contact lens materials than the static method. Specific differences based on lipid type and material surface structure were able to be identified that were not seen with the static method. Future studies on contact lenses biofouling should use non-static methodologies to more accurately mimic the in vivo environment.
Keywords: 477 contact lens •
583 lipids •
551 imaging/image analysis: non-clinical