**Study Overview:** This study tests a gel called **NEXAGON®** (lufepirsen ophthalmic gel) for eye problems known as **persistent corneal epithelial defects (PCED)**. PCED means there is an eye surface issue that doesn't heal properly. The research checks if the gel is safe and works well. **Study Details:** - This is a special kind of study where neither the participants nor the doctors know who gets the gel or a non-active gel. - The study has three parts: Screening (checking if you can join), Treatment (up to 8 weeks), and Follow-up (4 weeks). If the eye problem isn't better after this, you may get more gel treatment for 8 weeks. **Who Can Join:** - Must have PCED for at least 2 weeks without improvement from regular treatments. - Cannot have active eye infections or other eye conditions that might affect the study. - Cannot have been in another clinical trial recently or be using certain forbidden medicines. **Key Points:** - **Duration:** Up to 20 weeks if additional treatment is needed. - **Eligibility:** Must meet specific health criteria; some conditions can't be present. - **Participation:** Involves multiple visits and treatments; follow up for side effects and improvements.