RPE65-associated LCA/EOSRD accounts for approximately 5%–10% of cases and has been the subject of the most clinical trials to date.9RPE65 encodes a 65kD retinoid isomerase expressed in the RPE; a critical component of the retinoid (visual) cycle.33 34 As such, patients with RPE65 deficiency have a lack of 11-cis-retinal. Here, RPE65 is linked to severe early-childhood-onset retinal dystrophy.