Phase I/IIA Study of SAR422459 in Participants With Stargardt's Macular Degeneration

Inclusion Criteria: * Signed and dated written informed consent obtained from the participant and/or the participant's legally acceptable representative. * Diagnosis of SMD, with at least one pathogenic mutant ABCA4 allele on each chromosome. * Women of childbearing potential must had a negative pregnancy test at Day -1, and agree to use an effective form of contraception for at least three months, or be surgically sterile or postmenopausal, with the last menstrual period being over two years prior to enrollment. * Males must agree with their partner to use two forms of contraception for at least three months following SAR422459 administration. * Participants must agree to not donate blood, organs, tissues or cells for at least three months following SAR422459 administration. * Participants enrolled in France must be affiliated to or benefit from a social security regimen. Specific Inclusion Criteria Participant Group A: * Participants (18 years or older) with advanced SMD. * Visual acuity less than or equal to (\<=) 20/200 in the worst eye. * Severe cone-rod dysfunction with no detectable or severely abnormal full-field electroretinogram responses. Specific Inclusion Criteria Participant Group B: * Participants (18 years or older) with SMD. * Visual Acuity \<=20/200 in the worst eye. * Abnormal full-field electroretinogram responses. Specific Inclusion Criteria Participant Group C: * Participants (18 years or older) with SMD. * Visual acuity \<=20/100 in the worst eye…