This open-label study evaluated optogenetic gene therapy for restoring aspects of visual function in patients with advanced retinitis pigmentosa. Each of the 10 participants received a single intravitreal injection of an adeno-associated viral (AAV) vector encoding the red-shifted light-sensitive protein channelrhodopsin ChrimsonR into the worse-seeing eye. Light-stimulating goggles were used to activate ChrimsonR. A clinically meaningful improvement was defined as a decrease of at least 0.6 log units in the full-field stimulus threshold, corresponding to an approximately fourfold increase in light sensitivity.

Light sensitivity increased in seven participants, ranging from 2.0-fold to 62.3-fold, and six achieved a clinically meaningful improvement. A total of 34 ocular adverse events occurred in nine participants, including 23 mild and 10 moderate events. One severe event, transient…