The Effect of Contact Lens Coefficient of Friction on Lid Wiper Epitheliopathy and Tear Film Matrix Metalloproteinases
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Purpose: Contact lens discomfort (CLD) is a significant factor in patient discontinuation. Factors suggested in CLD include inflammatory and mechanical factors. Coefficient of Friction (CoF) is a contact lens property negatively correlated with contact lens comfort. Lid Wiper Epitheliopathy (LWE), a clinical sign, may demonstrate the impact of CoF on CLD. Matrix metalloproteinases (MMPS) are zinc proteases that break down extracellular matrix and are markers of inflammation. Little is known about LWE development and MMPs levels in new contact lens fits. We investigated the development of LWE and tear film MMP concentration in new contact lens fits over a one-week period. Methods: Twenty subjects without LWE staining were fit with a high CoF contact lens in one eye and a low CoF contact lens in the contralateral eye based on microtribometry data from Roba et al (2011). Lens/eye assignment was randomized. Two 20 microliter drops of Lissamine green were instilled in the lower conjunctival cul-de-sac. Digital images were taken and LWE graded. Ten microliters of tears were collected at baseline (BL), 2 hours (2H), and 7 days (7D) post-contact lens fit. Samples were analyzed for MMP-9, MMP-10, and MMP-13. Non-parametric statistics were performed when appropriate. Results: A difference in LWE was observed for all eyelids (P = .0004). A significant change was observed in the upper eyelids (P < .0001) but not the lower eyelids (P = .137). A difference in LWE from BL to 2H (P = .00006) and BL to 7D (P = .00004) was observed, but not between 2H and 7D (P = .437). A difference in LWE was observed from BL to 2H and BL to 7D for upper eyelids for each lens (Acuvue Oasys: BL-2H P = .003, BL-7D P = .002; Air Optix Night and Day: BL-2H P = .005, BL-7D P = .005). No difference was observed between the 2 eyelids at 2H or 7D post fit (P = .495 and P = .968). No changes in MMP-9, MMP-10 and MMP-13 were noted during the study period. Conclusion: LWE staining of the upper eyelid changed between BL and 1) 2H and 2) 7D post contact lens fit, but not between 2H and 7D. There was no difference in superior LWE staining between the lenses, suggesting that differing CoFs may not lead to different amounts of LWE. Contact lens wear in the early fitting period does not appear to alter tear film concentrations of MMP-9, MMP-10 or MMP-13.