The relationship between tear film MMP-9 and meibomian gland changes during soft contact lens wear.

To investigate the association between levels of MMP-9, a common marker of inflammation in tears, and changes to the meibomian glands accompanying soft contact lens (CL) wear. Flush tears were collected from: (1) three groups of CL wearers who had worn CLs on a daily basis for different durations (Short: 2 ± 1 years, Moderate: 5 ± 1 years and Long experience: 10 ± 2 years); (2) a group of previous CL wearers (PWs) who had ceased wear for at least 6 months; and (3) healthy non-wearers (NW) as a control group. Total MMP-9 and its inhibitor, tissue inhibitor of MMPs-1 (TIMP-1) concentration were established using sandwich enzyme-linked immunosorbent assay. The MMP-9: TIMP-1 ratio was calculated for every individual, and then the average of all ratios for each group were compared. The non-parametric statistical Kruskal Wallis one-way analysis of variance was used for comparison, with Dunn's testing post-hoc. Tear samples from 100 participants (51 females; mean age ± SD: 25.4 ± 4.1 years) were analysed. MMP-9 concentrations and MMP-9:TIMP-1 ratio were significantly different between groups (Kruskal Wallis p = 0.001 and p < 0.001 respectively), while the concentration of TIMP-1 did not vary statistically between study groups (Kruskal Wallis, p = 0.32). Post hoc analysis indicated that only CL wearers with short experience had MMP-9 concentrations that were significantly high compared to NWs (23.1 ± 17.9 ng/mL and 4.1 ± 4.1 ng/mL, respectively, Dunn p < 0.001). Additionally, the ratio of MMP-9 to TIMP-1 concentration was only significantly greater in CL wearers with short experience (mean ratio ± SD = 1.15 ± 0.76) when compared to NWs (0.19 ± 0.29, Dunn P < 0.001), CL wearers with moderate experience (0.37 ± 0.41; P = 0.01) and PWs (0.38 ± 0.36; P = 0.02). The early years of CL wear appear to be associated with increased expression of MMP-9 relative to its inhibitor TIMP-1. This may be indicative of low-level inflammation during this phase of wear. The role this plays in propagating dry eye disease and MGD in CL wear requires further exploration.

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Copyright © 2019 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Déclaration de conflit d'intérêts

Declaration of Competing Interest This work is original, has not been published and is not being considered for publication elsewhere. Part of this study was presented at the 2015 ARVO conference, Denver. There are no conflicts of interest for any of the authors that could have influenced the results of this work.