Abstract
Purpose: :
Recent epidemiological data has shown that the incidence of contact-lens related microbial keratitis remains unchanged over the past decade regardless of the widespread acceptance of silicone hydrogel contact lenses. The purpose of this study was to compare Pseudomonas binding rates to shed human corneal epithelial cells following long term daily and extended silicone hydrogel lens wear in the absence of chemically-preserved multi-purpose solutions.
Methods: :
The study design was a prospective, randomized, double-masked, single-center, parallel treatment groups clinical trial (National Clinical Trial NCT00344643). 115 patients completed the 12 month study wearing: (1) Lotrafilcon A (30N-EW, n=29) or (DW, n=32); (2) Lotrafilcon B (6N-EW, n=20) or (DW, n=21); (3) Galyfilcon A (DW, n=20). All patients were dispensed Clear Care to eliminate solution artifacts. All patients underwent a 30 day washout period prior to initiating lens wear; patients were assessed at baseline, 1, 3, 6, 9 and 12 months for the following outcome measures: (1) Pseudomonas aeruginosa (PA) binding to exfoliated corneal surface cells; (2) central epithelial thickness (CET); (3) epithelial surface cell desquamation (DESQ); results were compared to prior studies using multipurpose lens solutions.
Results: :
Using non-preserved lens solutions, DW had no significant effect on CET; there was a decrease in CET with EW which recovered (adapted) over 1 year (P<0.05). All lens wear (DW, EW) decreased DESQ with adaptive effects over 1 year (P<0.001). There was no significant difference in PA binding between lenses or modality of wear.
Conclusions: :
These results predict that the risk for PA-mediated contact lens keratitis should be the same for daily and extended silicone hydrogel lens wear in the absence of solution-induced corneal surface damage. In comparison to our previous studies using chemically-preserved multipurpose solutions with identical study protocols, these findings further suggest an important role for preservatives in the regulation of PA receptors on corneal epithelial cells.
Clinical Trial: :
www.clinicaltrials.gov NCT00344643
Keywords: contact lens • pseudomonas • cornea: clinical science