Preservative-free Topical Anesthetics for Post-PRK Pain

The goal of this interventional comparative study is to assess the efficacy and safety of a novel regimen of preservative-free unit-dose topical anesthetics for controlling early postoperative pain following single-step transepithelial PRK surgery. The main research questions to answer are: * Question 1: Are topical anesthetics effective in reducing post-PRK pain? * Question 2: Are short-term topical anesthetics toxic to the cornea? * Question 3: How to prevent abuse of topical anesthetics by patients at home? Participants were planned to undergo a bilateral single-step transepithelial PRK surgery to correct their refractive errors and received a standard post-PRK treatment regimen for both eyes. Additionally, one eye was offered a preservative-free topical anesthetic as an experimental group and the other eye was offered a preservative-free artificial tear as a control group.