Determination of the Lysozyme Deposit Curve in Soft Contact Lenses

PURPOSE.To determine lysozyme deposition as a function of time in soft, high-water content, ionic (group IV) contact lenses. METHODS.ACUVUE lenses were worn on an extended-wear basis (15 minutes, 2 hours, 4 hours, 6 hours, 8 hours, 1 day, 2 day, and so forth, up to 11 consecutive days). New lenses were dispensed at the beginning of each lens-wear period. After each wear cycle, lenses were analyzed for lysozyme deposition by high performance liquid chromatography. RESULTS.Lysozyme rapidly accumulated on lenses (15 minutes ∼55 μg/lens) and reached a plateau level by day 6 (∼1300 μg/lens). Most patients in the study showed a plateau range between 1200 and 1400 μg/lens. Six-month and 12-month follow-up studies with ACUVUE lenses showed minimal variation at the 5-day wear time point between the initial, sixth, and 12th month results. CONCLUSIONS.This study measured the rate of lysozyme buildup on lenses over time and demonstrated that lysozyme levels associated with group IV lenses reached a plateau after approximately 1 week of extended wear. Little variability was seen in lens lysozyme deposition up to 1 year later. The information derived from this study concerning the rate and variability of deposition has implications for the design and interpretation of cleaning studies and contact lens performance evaluations.