TEAR CHANGES IN CONTACT-LENS WEARERS FOLLOWING OVERNIGHT EYE CLOSURE

Purpose. Tear protein composition alters during eye closure, by becomi ng rich in secretory IgA (sIgA) and certain complement proteins. This may reflect altered ocular defense mechanisms during eye closure. Sinc e overnight wear of contact lenses (CLs) is associated with an increas ed risk of corneal infection and inflammation, this study aimed to qua ntify tear protein changes with overnight soft CL wear. Methods. Non-s timulated tears were collected from 9 CL wearers prior to CL wear (bas eline), after daily CL wear, and after 8 h sleep. Lenses were removed following wear and were extracted in 80% urea at 95 degrees C. Secreto ry IgA, complement C3 and C4, were measured using ELISA and total prot ein using the Pierce BCA assay. Assays were performed on tear samples and CL extracts. Results. Baseline tear protein concentrations were: 0 total tear protein (9.37 +/- 2.97 mg/mL), C3 (4.4 +/- 2.1 mu g/mL), C 4 (0.1 +/- 0.1 mu g/mL), and sIgA (0.84 +/- 0.34 mg/mL). There were no differences in any protein levels between daily CL wear and no CL wea r (p > 0.05). Following sleep, protein concentrations were: total tear protein (43.64 +/- 24.30 mg/mL), C3 (72.5 +/- 49.9 mu g/mL), C4 (6.7 +/- 5.2 mu g/mL), and sIgA (5.53 +/- 5.15 mg/mL). Total protein extrac ted from CLs after daily wear was 90 +/- 27 mu g/CL and, after overnig ht wear, 152 +/- 24 mu g/CL. Negligible levels of C3, C4 and sIgA were recovered from CL extracts. Uncomplicated daily use of soft CLs does not appear to alter certain tear proteins compared with baseline level s. Uptake of these proteins by the CL does not appear to deplete the t ear protein levels. Overnight levels of all tear proteins were increas ed, compared to daily CL wear.