Split intein-mediated protein trans-splicing expands AAV transfer capacity, thus overcoming the limited AAV cargo. However, non-mammalian inteins persist as trans-splicing by-products, and this could raise safety concerns for AAV intein clinical applications. In this study, we tested the ability of several degrons to selectively decrease levels of inteins after protein trans-splicing and found that a version of E. coli dihydrofolate reductase, which we have shortened to better fit into the AAV vector, is the most effective. We show that subretinal administration of AAV intein armed with this short degron is both safe and effective in a mouse model of Stargardt disease (STGD1), which is the most common form of inherited macular degeneration in humans. This supports the use of optimized AAV intein for gene therapy of both STGD1 and other conditions that require transfer of large genes. Display omitted Intein-mediated protein trans-splicing (PTS) expands AAV gene transfer capacity. However, non-mammalian inteins persist as trans-splicing by-products. Here, we show that ecDHFR selectively degrades inteins after PTS and that AAV intein vectors armed with this degron are both safe and effective in the retina of a mouse model of genetic blindness.