Polyvinyl alcohol is a wetting agent that could reduce the symptoms of dry eye and contact lens discomfort. Currently, only one lens type, nelfilcon A (DAILIES AquaComfort Plus), releases polyvinyl alcohol. The concept of releasing this agent from contact lenses could be applied to other lens materials.
The purpose of this study was to measure the release of polyvinyl alcohol from commercially available hydrogel daily disposable contact lenses using refractive index and iodine-borate methods.
Etafilcon A, omafilcon A, and nelfilcon A were soaked in phosphate-buffered saline and 0.2% trifluoroacetic acid/acetonitile for 24 hours to remove residual blister pack components. The lenses were then incubated in a 10-mg/mL solution of polyvinyl alcohol for 24 hours. After the incubation period, the lenses were placed in 2 mL of phosphate-buffered saline. At specified time intervals, t
= 0.5, 1, 2, 4, 8, 12, and 24 hours, the samples were evaluated using refractive index and an iodine-borate assay. Polyvinyl alcohol uptake was determined by extracting the lenses with methanol for 24 hours.
There were no differences in the uptake of polyvinyl alcohol between lens types (P
> .05). The release of this wetting agent for all lens types followed a burst-plateau profile after the first 30 minutes (P
> .05). Nelfilcon A had a slightly higher release of polyvinyl alcohol (P
< .05) than did etafilcon A but was similar to omafilcon A (P
The results suggest that the contact lenses tested in this study have similar efficiency in delivering polyvinyl alcohol.