Soft lens extended wear affects epithelial barrier function

Objective: To explore the impact of eye closure and soft contact lens exten ded wear (SCLEW) on epithelial permeability to fluorescein (P-dc). Design: A prospective cohort study. Thirty-one noncontact lens (CL) wearers participated, Intervention: The effects of eye closure on P-dc were evaluated by comparin g morning (AM) and afternoon (PM) measurements on non-CL subjects. The effe cts of SCLEW on P-dc were determined by measuring P-dc before beginning SCL EW and then after 2, 4, and 12 weeks of SCLEW. Main Outcome Measures: P-dc measured in the morning versus the afternoon an d before versus after SCLEW was examined. Results: Analyses of P-dc were done using the natural logarithm (In), The m ean +/- standard error (SE) In(P-dc) measured in the AM versus PM on 16 non -CL wearers did not differ significantly (-2.56 +/- 0.16 vs. -2.69 +/- 0.15 , respectively; P = 0.46), In contrast, the mean +/- SE In(P-dc) in 15 subj ects after 2 (-1.73 +/- 0.183, P < 0.001), 4 (-1.59 +/- 0.188, P < 0.001), and 12 weeks (-1.99 +/- 0.206, P = 0.02) of SCLEW was substantially greater than that measured before lens wear (-2.42 +/- 0.159 In(nm/sec)). Interest ingly, the mean +/- SE In(P-dc) measured in the afternoon on seven subjects after 13 weeks of SCLEW was similar to their average baseline In(P-dc) (-2 .62 +/- 0.27 vs. -2.52 +/- 0.243, respectively; P = 0.54), Further analysis showed that P-dc was highest in the morning and decreased approximately 12 .5%/hour (P < 0.001) during the day. Conclusions: Sleeping without CLs does not appear to alter P-dc; however, 2 weeks of SCLEW caused a 99% increase in permeability without observable ch anges by slit-lamp examination. Increases in P-dc appear greatest in the mo rning after SCLEW and then decrease exponentially during the day, Whether c hanges in P-dc will predict CL-associated keratopathy needs further study.