Effect of Preserved Versus Preservative-Free Artificial Tears on the Corneal Epithelial Thickness Mapping by MS-39 in Dry Eye Patients.

Purpose: To compare clinical and corneal epithelial changes between preservative and preservative-free artificial tear therapy using the MS-39 in patients with dry eye disease (DED). Methods: This prospective interventional comparative study included 88 eyes of 44 patients. Preserved artificial tears were given for the left eye (group A) and preservative-free artificial tears for the right eye (group B). They were evaluated before and 3 months after treatment using MS-39. The dry eye parameters and corneal epithelial thickness were recorded. Results: There was an increase in the NIBUT and improvement in the severity by OSDI score (p-value < 0.001) in each group. There was no significant difference in the mean NIBUT between the two groups (p-value = 0.470). Improvement in the OSDI score (p-value = 0.026) and mean post-treatment epithelial thickness in the central, paracentral superior, and peripheral inferior epithelial areas were significant in the preservative-free group than the preservative one (p-value = 0.033, 0.034, and 0.023, respectively). Conclusion: Although both preservative-free and preserved artificial tears show an increase in epithelial thickness using MS-39 and improvement in OSDI, preservative-free artificial tears show superiority, subjectively and objectively, compared to preserved artificial tears using even lighter preservatives, being a safer option for long-term application.