Study protocol
After submitting a written informed consent for study participation at Visit 1, the participants were assigned a screening number. If determined to be eligible for study participation based on inclusion/exclusion criteria in accordance with the study protocol at screening, participants were not allowed to use eye drops, including treatment agents for DED, during the 2-week pre-study washout period. Any participant who did not use other eye drops before randomization and met inclusion/exclusion criteria at Visit 2 was randomized to either of three treatment arms, such as the 1% rebamipide, 2% rebamipide, and placebo groups. Each of the eye drop formulations was instilled four times daily for 12 weeks. Packages of clinical trial drugs was established and the randomization scheme was generated using SAS Version 9.4 or higher (SAS Institute, Cary, NC, USA), and the list was delivered to the interactive web response system (IWRS) developer and personnel who were responsible for the packaging of the clinical trial drugs. The randomization number and the batch number of clinical trial drugs were confirmed by the IWRS.All the randomized participants were allowed to receive study treatments for 12 weeks, and were instructed to visit each study center at 4, 8 and 12 weeks for assessment of efficacy, safety, and eye tolerability.