The effect of nonpreserved care solutions on 12 months of daily and extended silicone hydrogel contact lens wear.

PURPOSE To determine the effects of nonpreserved care solutions on human corneal epithelium in long-term daily wear (DW) compared with overnight (extended) wear (EW) of hyper-oxygen-permeable silicone hydrogel contact lenses. METHODS This was a prospective, randomized, double-masked, single-center, parallel treatment group clinical trial (NCT 00344643). One hundred twenty-one patients completed the 13 month study: (1) Lotrafilcon A (30 night EW, n = 29; DW, n = 32); (2) Galyfilcon A (DW, n = 20); and (3) Lotrafilcon B (6 night EW, n = 20; DW, n = 21). Irrigation chamber collection of corneal surface cells (OD) and confocal microscopy (OS) were performed at baseline, 1 week; and 1, 3, 6, 9, and 12 months of EW. The main outcome measures were: (1) Pseudomonas aeruginosa (PA) binding to exfoliated corneal surface cells; (2) central epithelial thickness (CET); and (3) epithelial surface cell exfoliation rate (desquamation). RESULTS DW had no significant effect on CET; there was a decrease in CET with EW that recovered (adapted) over 1 year (Lotrafilcon B, P < 0.05). All lens wear (DW, EW) decreased desquamation with adaptive effects over 1 year (P < 0.001). There was no significant difference in PA binding between lenses or modality of wear. CONCLUSIONS PA binding to corneal epithelial cells is a prerequisite for infection, and no binding indicates no lens-enhanced risk of infection. In contrast to prior studies of preserved lens-care products, the absence of a change in the PA binding data results predict that the risk for PA CTL-keratitis should be similar for daily and extended silicone hydrogel lens wear over 1 year when preservative-free care solutions are used.