ABCA4 and severe early-childhood-onset retinal dystrophy: To determine which AAV-based strategy most efficiently transduces large genes in the retina, we compared them side-by-side in HEK293 cells and in mouse and pig retina using EGFP, ABCA4 or MYO7A. We then used the dual AAV trans-splicing and hybrid strategies, which were the most efficient for transducing PR as well as RPE, to rescue the retinal phenotype of the Abca4−/− and sh1 mouse models of STGD and USH1B.