This interventional study is being conducted with an investigational gene therapy treatment called ABBV-RGX-314 (also known as RGX-314) and is being developed as a potential one-time gene therapy treatment for neovascular (wet) age-related macular degeneration (wet AMD or nAMD). The typical treatment for nAMD is frequent injections of anti-VEGF therapy. Researchers are testing ABBV-RGX-314 to see if it has similar effects as the current approved standard of care, such as Lucentis® or Eylea® injections. The duration of this study will be up to 52 weeks or for ranibizumab control participants who cross over to ABBV-RGX-314 after week 52, up to 80 weeks post-randomization. The primary outcome measure for this investigational study is to evaluate the mean change in best-corrected visual acuity (BCVA) for ABBV-RGX-314 compared with ranibizumab monthly at the Week 40 visit.