PURPOSE: Report the clinical effects and discomfort of using 0.1% hyaluronic acid (HA [Kynex 1 METHODS: This study was designed as a prospective, crossover, randomized, and double-blind study. Patients aged >
19 years with DED level 2 or higher, corneal staining score >
1, and tear break-up time (TBUT) <
10s were included. Sixty patients were randomly assigned to two groups. Patients in group 1 were instilled with 0.1% HA for four weeks and then 0.3% HA for the next four weeks. Group 2 patients were instilled with the eye drops in the reverse order of group 1. Patients were evaluated using a corneal staining score, TBUT, and the Standardized Patient Evaluation of Eye Dryness (SPEED) questionnaire at baseline, four weeks, and eight weeks. RESULTS: In both groups, 0.3% HA showed an increasing trend in TBUT, although the difference was not statistically significant. Changes in the Schirmer test were greater in group 2, but this difference was also not statistically significant. The corneal staining score improved in both groups, with no statistically significant difference. While 0.3% HA was more effective than 0.1% HA according to the absolute value, this difference was not statistically significant. There was no difference between the two groups in the SPEED questionnaire evaluation that assessed aspects of discomfort, such as blurred vision, foreign body sensation, and burning sensation. CONCLUSION: 0.3% HA was more effective for treating DED, although the difference was not statistically significant. In terms of discomfort, 0.3% HA showed no difference compared to 0.1% HA. Using both 0.1% HA and 0.3% HA in a tailored treatment approach can improve patient comfort and treatment outcomes.