Achromatopsia is a hereditary form of day blindness, caused by cone photoreceptor dysfunction. A sheep model of this disease was characterized by us, and has been utilized successfully to test the safety and efficacy of achromatopsia gene therapy. The rescue effect has, so far, been maintained for over 8 years. Following FDA approval, clinical trials of CNGA3 achromatopsia gene therapy in patients were initiated last year.