title: Tear changes in contact lens wearers following overnight eye closure.
abstract: OBJECTIVE
  Tear protein composition alters during eye closure, by becoming rich in secretory IgA (sIgA) and certain complement proteins. This may reflect altered ocular defense mechanisms during eye closure. Since overnight wear of contact lenses (CLs) is associated with an increased risk of corneal infection and inflammation, this study aimed to quantify tear protein changes with overnight soft CL wear.
  
  
  METHODS
  Non-stimulated tears were collected from 9 CL wearers prior to CL wear (baseline), after daily CL wear, and after 8 h sleep. Lenses were removed following wear and were extracted in 80% urea at 95 degrees C. Secretory IgA, complement C3 and C4, were measured using ELISA and total protein 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 micrograms/mL), C4 (0.1 +/- 0.1 micrograms/mL), and sIgA (0.84 +/- 0.34 mg/mL). There were no differences in any protein levels between daily CL wear and no CL wear (p > 0.05). Following sleep, protein concentrations were: total tear protein (43.64 +/- 24.30 mg/mL), C3 (72.5 +/- 49.9 micrograms/mL), C4 (6.7 +/- 5.2 micrograms/mL), and sIgA (5.53 +/- 5.15 mg/mL). Total protein extracted from CLs after daily wear was 90 +/- 27 micrograms/CL and, after overnight wear, 152 +/- 24 micrograms/CL. Negligible levels of C3, C4 and sIgA were recovered from CL extracts.
  
  
  CONCLUSIONS
  Uncomplicated daily use of soft CLs does not appear to alter certain tear proteins compared with baseline levels. Uptake of these proteins by the CL does not appear to deplete the tear protein levels. Overnight levels of all tear proteins were increased, compared to daily CL wear.
authors.affiliation: Cornea and Contact Lens Research Unit, School of Optometry, University of New South Wales, Sydney, Australia. f.stapleton@cclru.unsw.edu.au
authors.forename: F
authors.initials: F
authors.lastname: Stapleton
authors.forename: M D
authors.initials: MD
authors.lastname: Willcox
authors.forename: C A
authors.initials: CA
authors.lastname: Morris
authors.forename: D F
authors.initials: DF
authors.lastname: Sweeney
mesh_terms: D000328:Adult; D003176:Complement C3 / Q000378:metabolism; D003181:Complement C4 / Q000378:metabolism; D003262:Contact Lenses, Extended-Wear; D003263:Contact Lenses, Hydrophilic; D004797:Enzyme-Linked Immunosorbent Assay; D005136:Eye Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000378:metabolism; D008297:Male; D011485:Protein Binding; D012683:Sensory Deprivation; D012890:Sleep; D013666:Tears / Q000378:metabolism*; D000267:Tissue Adhesions
chemical_list: D003176:Complement C3; D003181:Complement C4; D005136:Eye Proteins; D007071:Immunoglobulin A, Secretory; C042434:tear proteins