Open-Label Study to Evaluate the Safety, Tolerability, and Efficacy of Gene Therapy (SPVN20) in Subjects With Rod-Cone Dystrophy

Inclusion Criteria: 1. Age ≥ 18 years old at enrollment. 2. Participant with a genetically confirmed clinical diagnosis of advanced RCD in both eyes due to non-syndromic RCD. 3. Participants enrolled in the Dose-Escalation cohorts must have a BCVA meeting the study eye criteria. 4. Documented preservation of foveal cone cell bodies in the study eye (as shown on SD-OCT imaging). 5. Participant with a history of formed vision. 6. Participant willing and able to provide informed consent. Exclusion Criteria: 1. Participant participating in another clinical trial and receiving an investigational medicinal product (IMP) within either 5 half-lives of that IMP, or 90 days prior to the injection of SPVN20. 2. Participant with cortical visual impairment. 3. Participant with systemic disease or other pathology not related to their diagnosis of RCD, and whose symptoms or associated treatments may affect vision. 4. Participant with known allergies to corticosteroids, or who will be unable to tolerate the corticosteroid regimen. 5. Participant who has received immunosuppressive therapies or any other therapy known to impact the immune system during the last month prior to SPVN20 administration. 6. Active ocular inflammation or recurrent history of idiopathic or autoimmune-associated uveitis. 7. Participant known to be allergic to any of the delivery vehicle constituents or to any other drugs planned to be used during the clinical study. 8. Active alcohol or substance abuse. 9. Participant positive for human immunodeficiency virus (HIV) or any other systemic immunocompromising disease. 10. Participant with active Hepatitis B or Hepatitis C. 11. Female participant currently pregnant or breastfeeding or intending to become pregnant. 12. Participant with clinically active ocular infection of herpetic diseases. 13. Participant with active coronavirus disease (COVID-19) infection. 14. Participant who received any vaccination/immunization within 28 days prior to screening and/or during screening. 15. Participant who previously received any gene therapy product, stem cell therapy, cell-based therapy for ocular or non-ocular disease. 16. Participant with a retinal implant at enrollment. 17. Participant with pre-existing eye conditions that would interfere with the interpretation of study endpoints, or increase the risk of surgical complications. 18. Participant with significant media opacity impacting evaluation of the retina or vitreous. 19. Participant who had intraocular surgery within 90 days of study treatment administration. 20. Participant with history of corticosteroid-induced raised IOP of \>25 mmHg following corticosteroid exposure, despite topical IOP-lowering pharmacologic therapy. 21. Participant with history of unresolved rhegmatogenous retinal detachment in the fovea. 22. Participant with history of unresolved ocular hypotony. 23. Participant unwilling or unable (based on the Investigator's judgment) to comply with the study protocol. 24. Participant with any condition that would not allow them to complete follow-up examinations during the study and, in the opinion of the Investigator, would make them unsuitable for the study. 25. Participant currently taking restricted classes of medications listed in protocol 26. Participant with ongoing cardiac or neurological disorders not managed by a restricted medication can be excluded based on the Investigator's judgement. 27. Women of childbearing potential (WOCBP) and men and/or their partner(s) of childbearing potential who do not agree to use a highly effective contraceptive method.