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Clinicians are likely familiar with contact lens wearers complaining that their eyes “feel like they have sand in them by the end of the day.” While previous studies have described the role of inflammation in dry eye disease (DED), researchers in the School of Optometry at University of Alabama furthered this work by analyzing tear samples for 50 inflammatory proteins in symptom-free contact lens wearers and those with contact lens-related dry eye (CLDE), according to the paper published in Contact Lens & Anterior Eye.
The study looked at 100 healthy volunteers 18 to 39 years old who wore daily soft contact lenses for at least 1 year for ≥6 hours per day, 5 days a week. Individuals with prior corneal refractive surgery or hayfever were excluded. They grouped the patients into 2 cohorts, normal contact lens wearers and those with CLDE, based on 3 criteria: tear film break-up time, results of the Contact Lens and Dry Eye Questionnaire, and the ratio of total vs comfortable wear time. With contact lenses in place, an examiner collected tear samples bilaterally from the inferotemporal tear meniscus, avoiding contact with lid or ocular surface.
The mean tear volume of 7.12 μL collected from normal lens wearers was significantly more than the 5.90 μL gathered from CLDE participants (P =.002). Similarly, researchers noted higher total tear protein of 32.49 μg in normal patients’ tears vs 26.22 μg in tears of those in the CLDE group (P =.04). However, protein concentration was comparable between cohorts (P =.28).
Participants in the CLDE group displayed a number of considerably increased cytokines and chemokines in their tears, according to the study. Three cytokines were greater by 3 times or more for this group when compared with controls, including interleukin (IL)-13 (P =.001), eotaxin/CCL11 (P =.016), and IL-1 receptor antagonist (P =.013). Ten were significantly increased, such as granulocyte-colony stimulating factor (GCSF) (P =.005), GRO-α/CXCL1 (P =.003), IL-12 p70 (P =.002), IL-8 (P =.001), IL-7 (P =.001), IL-15 (P =.001), and 4 others.
While a number of prior studies demonstrate little difference in tear protein concentration between contact lens wearers with and without symptoms, others show a variety of increased inflammatory mediators in tears of lens wearers with dry eye. These inconsistencies for specific markers may result from factors including lab analysis checking fewer mediators, and smaller population samples. Alternately, the current study’s authors note that proteins which differed between groups varied by 2 to 4 times the concentration, more clearly showing tear film impact.
Researchers note that certain markers such as IL-1β and stress responders such as IL-1 did not show differences, and speculate this could be due to adaptation of wearers, adherence of protein to the contact, or a possible limitation of the customized immunoassay. Other limitations include a slight alteration in concentration introduced by pooling 10 samples in each cohort for a representative value, and exclusion of noncontact lens wearers.
The study concludes that “inflammation may be involved in the etiology of contact lens-related dry eye and discomfort commonly experienced by contact lens wearers.”
Disclosure: Study authors have declared affiliations with the medical device, biotech, or pharmaceutical industries. Please see the original reference for a full list of authors’ disclosures.
Reference
Ramamoorthy P, Khanal S, Nichols JJ. Inflammatory proteins associated with contact lens-related dry eye. Contact Lens & Anterior Eye. Published online April 3, 2021. doi:10.1016/j.clae.2021.101442
