Gene therapy is designed to insert a copy of a corrected gene into retinal cells. The hope is to return cell function back to normal and the treatment has the potential to stop disease progression. This therapy will not restore impaired vision back to normal. The research is being undertaken by a partnership between Sanofi and Oxford BioMedica. A Lentiviral vector is used to deliverer normal genes to the eye via a subretinal injection. The therapy is known as SAR422459 and it is in Phase I/II trials at present (2018).