Diabetic Retinopathy (DR) is an eye condition caused by diabetes that can lead to vision problems if untreated. This study is testing a new gene therapy called **surabgene lomparvovec** (sura-vec) to see if it can help prevent these issues. It's given in the **suprachoroidal space (SCS)**, an area in the eye, to people with DR but without a specific kind of swelling called **center-involved diabetic macular edema (CI-DME)**.

This study has three parts and plans to include 576 adults in the US and Puerto Rico. Participants will be randomly placed in groups to receive different treatments, including sura-vec, steroids, or a fake treatment (sham), and will be followed for five years.

• The study will last for 5 years, with regular clinic visits required.
• If you don't get sura-vec initially, you might have a chance to try it later.
• Participants may experience a higher treatment burden compared to their current care.