Accelerated photostability testing of precision UVTM contact lenses

Abstract

Precision UV^TM contact lenses were photoaged beyond their expected lifetime in an accelerated manner with a SUNTEST® CPS⁺ system, which is a solar spectrum equivalent. Ultraviolet spectra of lenses irradiated for 30 h in saline at 41°C and 44°C at the highest power setting were statistically indistinguishable from those measured prior to the exposure. In a similar experiment run at 79°C, the UVB range of the spectra showed small but statistically significant differences, whereas the UVA range of the spectra were not distinguishable. Lenses photoaged at half power and twice the time at 43°C gave UV spectra that could be distinguished. Refractive indices of lenses were indistinguishable before and after irradiation. Eluted materials could not be detected in the saline used to maintain lenses in any irradiation experiment. Lens parameters and water contents remained within manufacturing specifications before and after irradiation.