The 1-Step Versus 2-Step Subretinal Injection Trial (1,2-SIT)—A Randomized Controlled Trial to Compare Drug Reflux Following Subretinal Injection

This study demonstrates that drug loss following SRI ranged from 0.4% to 19.8% (mean 4.3%). There is no significant difference between 1-step and 2-step SRI in the mean proportion of drug reflux, duration of surgery, change in neural retinal thickness, or change in BCVA. However, there is a significantly greater variability in reflux for 1-step injection compared to 2-step injection. AAV yields are not affected by 0.1 mg/mL sodium fluorescein, nor is RPC viability. These data suggest that sodium fluorescein may be an appropriate means of tracking subretinal AAV gene therapy and retinal cell therapy quantitatively and that the 2-step SRI approach is preferable to 1-step SRI to ensure consistency in drug delivery.