Safety and Efficacy Study of NGGT001 in Bietti Crystalline Corneoretinal Dystrophy

Inclusion Criteria: 1. Age ≥ 18 years old; 2. Gender unlimited. 3. Diagnosed as crystalline retinal degeneration (BCD). 4. Molecular diagnosis confirms CYP4V2 mutation. 5. The best corrected visual acuity is less than 20/60. 6. Agree to take contraceptive measures within 1 year from the start of the study until administration. 7. Voluntarily sign an informed consent form. Exclusion Criteria: 1. Insufficient number of photoreceptor cells in the retina, such as retinal thickness less than 100 μ m. Or no atrophy or pigmentation in the posterior pole area\<3- Retinal disc. 2. The presence of choroidal neovascularization or other eye lesions caused by BCD, which researchers believe may affect surgical procedures or interfere with the interpretation of clinical endpoints. 3. The use of therapeutic drugs within the first 6 months of enrollment may affect experimental observation, such as Lucentis, Avastin, Conbercept, Triamcinolone acetonide, steroids, etc; 4. The treatment eye has undergone intraocular surgery, such as PDT, vitrectomy, periocular vascular bypass surgery, etc., or requires intraocular surgery during clinical research, such as cataract surgery, retinal laser therapy, etc; 5. Used or may use systemic medications that may cause eye damage, such as psoralen, tamoxifen, etc; 6. Highly sensitive or allergic to the ingredients in the experimental drug (with a history of allergies to two or more drugs or foods); 7. Abnormal and clinically significant physical examination, vital signs, laboratory tests (such as blood routine, urine routine, blood biochemistry, coagulation function, immunological tests, etc.), or abnormal indicators deemed clinically significant by researchers; 8. There are diseases or medical histories that may affect drug safety or internal processes, especially cardiovascular, liver, kidney, endocrine, digestive, lung, neurological, hematological, tumor, immune or metabolic disorders that researchers consider clinically significant. 9. Participated in clinical trials of other drugs or medical devices within 3 months prior to enrollment; 10. Female patients during pregnancy or lactation; 11. Other researchers believe that it is not suitable to participate in the study.