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RESEARCH PRODUCT

A 12-month Prospective Study of Tear Osmolarity in Contact Lens Wearers Refitted with Daily Disposable Soft Contact Lenses

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SIGNIFICANCE Tear osmolarity has been reported as one of the best diagnostic tests for dry eye disease and its management. Contact lens wear is thought to influence tear homeostasis. Understanding how regular wear of contact lenses and their type affect tear osmolarity is important. PURPOSE The purpose of this study was to assess changes in tear osmolarity and ocular symptoms over a period of 12 months following refitting contact lens wearers with daily disposable contact lenses. METHODS Fifty subjects aged (mean ± SD) 26 ± 4 years were refitted with either silicone-hydrogel (delefilcon A, SiHy, n = 34) or hydrogel (omafilcon A, Hy, n = 16) daily disposable soft contact lenses. Study included seven visits: baseline measurements without contact lenses; two visits for contact lens fit and selection; follow-up measurements after 3, 6, and 12 months of contact lens wear; and a post-study visit without contact lenses. Lens type selection was based on a set of objective measurements. Subjects were instructed to follow strict wearing rules. Impedance-based osmometer was used to collect samples from the lower tear meniscuses. The Ocular Surface Disease Index (OSDI) and the eight-item Contact Lens Dry Eye Questionnaire were used to assess subject-reported ocular symptoms and contact lens discomfort, respectively. RESULTS Downward trend of tear osmolarity was noted over the time course of study. Statistically significant differences were noted in tear osmolarity (Friedman test, χ = 21.91 [P < .001], and χ = 13.89 [P = .003]) for the right and left eyes, respectively. A statistically significant decrease in tear osmolarity was apparent only for initially symptomatic subjects (for OSDI ≥13: χ = 26.25, P < .001; for OSDI <13: χ = 5.65, P = .13). Statistically significant differences were not noted in OSDI and the eight-item Contact Lens Dry Eye Questionnaire between the baseline and 12-month visit (χ = 5.92 [P = .12] and R = 0.015 [P = .87], respectively). There was a difference between baseline and post-study visits (P = .002) in OSDI, showing lower score at the latter visit. CONCLUSIONS Refitting with daily disposable contact lenses was demonstrated to lower tear osmolarity.