Comparing thermal and chemical disinfection systems for the etafilcon A 58% water content contact lens

Several high water content lenses (greater than or equal to 55%) have been approved for either thermal or chemical disinfection. Thermal disinfection has been reported to be contraindicated for higher water content lenses, yet no studies have been performed to show this with a high water content daily or extended wear lens approved for thermal disinfection. A three-phase clinical study was initiated in which eight previously successful soft contact lens wearers were fitted with etafilcon A lenses. The subjects were placed on an approved thermal disinfection regimen for the lens on the right eye, and on an approved chemical disinfection regimen for the lens on the left eye. Results show that thermal disinfection of the etafilcon A lenses results in lens discoloration and reduced lens performance over a short period of time, as compared to the chemically disinfected lenses which showed no compromise in fit or any discoloration. Possible causes of the poor performance and appearance of the thermally disinfected lenses are discussed.