Short-term Changes in Tear Osmolarity after Instillation of Different Osmolarity Eye Drops in Patients with Dry Eye

This study comprised 80 patients with dry eye whose tear osmolarity measurement using the TearLab ® os molarity system was 300 mOsm/L or greater. Patients who had external ocular disease, glaucoma, or other concomitant ocular pathology were excluded. After being randomly divided into four groups, the participants received different kinds of SH eye drops as follows: Groups 1–3 were given one of three concentrations (0.1%, 0.15%, and 0.3%) of isotonic drops, while Group 4 received 0.18% hypotonic SH eye drops. The tear osmolarity concentrations were evaluated at baseline and again at 1-, 5-, and 10-minutes after instillation of each eye drop. Tear osmolarity showed a significant decrease after instillation of four types of SH eye drops after up to 10 minutes compared to baseline. Patients who received hypotonic SH eye drops showed an enhanced decrease in tear osmolarity compared with the isotonic SH eye drops after 1 minute (p < 0.001) and 5 minutes (p = 0.006), but the difference was not significant at 10 minutes (p = 0.836). The enhanced immediate effect of hypotonic SH eye drops at lowering tear osmolarity in patients with dry eye seems to be limited unless these drops were used frequently.