Tear Inflammatory Molecules in Contact Lens Wearers: A Literature Review

Background: Numerous studies have analysed the effect of using different Contact Lenses (CLs) or care solutions, and suffering discomfort or diseases associated with CL wear on the inflammatory mediator release into the tears. Objective: To summarize the published data on tear inflammatory molecules related to CL use. Methods: A PubMed-NCBI search has been conducted and those publications which carried out original investigations including the analysis of tear inflammatory mediators in CL wearers were selected. Results: Forty-three articles, from 1990 to 2019, have been included. Wearing hydrogel CLs, rigid gas permeable CLs, and special designs for irregular corneas in keratoconus patients (CLs with keratoconic design, hybrid CLs, piggyback fit, and scleral CLs) have been reported to alter the concentration of several molecules in tears. Moreover, there seems to be an effect of the wearing time and schedule, CL materials and designs, and care solutions used. Regarding CL discomfort, its relation with inflammatory mediators is not clear. However, some diseases associated to CL wear, such as giant papillary conjunctivitis, CL induced acute red eye, CL induced peripheral ulcer, and acanthamoeba keratitis have been related to the release of certain inflammatory mediators, which may serve as potential biomarkers. Conclusion: There is evidence suggesting that different aspects of CL wear alter the inflammatory mediator profile in tears, which may indicate an inflammatory state of the lacrimal functional unit. However, more studies need to be carried out to better understand how this inflammatory process works and its repercussion on the different aspects of CL wear.