Switching from preserved to preservative-free artificial tears and short-term change in dry eye symptoms and signs: a prospective self-controlled clinic cohort.

BACKGROUND: Artificial tears are first-line treatment for dry eye disease, but the clinical value of removing preservative exposure in routine practice remains incompletely defined. METHODS: This prospective, self-controlled, single-center observational study was conducted from January to June 2025. Adults with symptomatic dry eye who had used preserved artificial tears for at least 30 days underwent a routine-care switch to preservative-free tears and were followed at baseline, week 2, and week 6. The primary endpoint was change in full OSDI at week 6, analyzed with linear mixed-effects models using all available repeated data. RESULTS: A total of 140 patients were enrolled and 137 completed the week-6 primary-endpoint visit. Mean OSDI decreased from 38.7 ± 14.9 at baseline to 24.3 ± 13.2 at week 6; the model-based mean change was - 14.1 points (95% CI, - 16.5 to - 11.7; p < 0.001). TBUT increased from 4.8 ± 1.9 s to 6.9 ± 2.3 s, with a mean change of +2.1 s (95% CI, 1.7 to 2.5; p < 0.001). Ninety-one of 137 completers (66.4%) achieved an OSDI improvement of at least 10 points. Oxford staining improved and Schirmer I increased modestly but significantly. CONCLUSIONS: In this prospective self-controlled clinic cohort, switching from preserved to preservative-free artificial tears was associated with statistically significant and clinically meaningful short-term symptom improvement and supportive ocular-surface sign changes. However, the absence of a continuation control and concurrent formulation or bottle changes precludes attributing these improvements to preservative removal alone.