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.