Inclusion Criteria include: 1. Male or female subjects with documented mutations in both alleles of the CNGB3 gene; 2. Retinal disease consistent with a clinical diagnosis of achromatopsia; 3. At least 18 years of age for Groups 1, 2, 3, 4, 5 and 6. At least 6 years of age for Group 4a, and 4-8 years of age for Groups 5a and 7; 4. Able to perform tests of visual and retinal function; 5. Visual acuity in the study eye not better than 55 ETDRS letters (Snellen equivalent 20/80) based on the average of two examinations at the baseline visit; 6. Acceptable laboratory parameters; 7. For females of childbearing potential: A negative pregnancy test within 2 days before administration of study agent. Exclusion Criteria include: 1. Best-corrected visual acuity difference between the two eyes of \> 15 ETDRS letters (3 lines); 2. Evidence of degenerative myopia in the study eye; 3. Pre-existing eye conditions that would contribute to vision loss in either eye or increase the risk of subretinal injection in the study eye.