Extension Study to Study PQ-110-001 (NCT03140969)

Inclusion Criteria: * Subjects who completed participation in the study PQ-110-001 and who may derive benefit from continued treatment with QR 110, as assessed by the Investigator, in consultation with the Medical Monitor * Persistence of detectable outer nuclear layer (ONL) in the area of the macula in the opinion of the Investigator, as determined by OCT. * Clear ocular media and adequate pupillary dilation to permit good quality retinal imaging, as assessed by the Investigator. * An adult (≥ 18 years) willing and able to provide informed consent for participation OR a minor (6 to \< 18 years) with a parent or legal guardian willing and able to provide written permission for the subject's participation prior to performing any study related procedures, and pediatric subjects able to provide age-appropriate assent for study participation. * Female subjects who have reached menarche and male subjects must either practice true abstinence in accordance with their preferred and usual lifestyle, or agree to use acceptable, highly effective methods of contraception for up to 3 months following their last dose QR-110. Acceptable methods of contraception are defined in the protocol. Women of non-childbearing potential may be included without the use of adequate birth control, provided they meet the criteria in the protocol. Exclusion Criteria: * Any contraindication to IVT injection according to the Investigator's clinical judgment and international guidelines (Avery 2014). * Safety issue during study PQ-110-001 that may compromise subject safety when continued dosing, as determined by the Investigator, and in consultation with the Medical Monitor. * Any ocular or systemic disease or condition (including medications and laboratory test abnormalities) that could compromise subject safety or interfere with assessment of efficacy and safety, as determined by the Investigator and in consultation with the Medical Monitor. * Pregnant or breast-feeding female.