• Neuro-Ophthalmology/Orbit, Retina/Vitreous

    Review of: Partial recovery of visual function in a blind patient after optogenetic therapy

    Sahel J, Boulanger-Scemama E, Pagot C, et al. Nature Medicine, July 2021

    For the first time, investigators report using an optogenetic treatment to restore partial vision in a patient with retinitis pigmentosa (RP).

    Study design

    The phase 1/2a PIONEER study is a multicenter, open-label, nonrandomized dose-escalation trial designed to evaluate the safety and tolerability of an optogenetic treatment. Study participants with nonsyndromic RP received a single injection of an adeno-associated viral vector encoding ChrimsonR (GS030-DP) to the worse-seeing eye and light stimulation via engineered goggles (GS030-MD). The goggles activated optogenetically transduced retinal ganglion cells by projecting light pulses onto the retina in real time based on local changes in light intensity.

    By the end of 2020, 3 cohorts of 7 total patients had received treatment; however, only one patient could perform all 15 postinjection training sessions during the COVID-19 pandemic. The 58-year-old patient had visual acuity limited to light perception preoperatively. Researchers conducted visual function testing and electroencephalographic recordings.

    Outcomes

    While wearing the goggles, the patient could use the treated eye to perceive, locate, count, and touch various objects. Using multichannel electroencephalogram, the authors detected changes in cortical activity above the visual cortex that corresponded to object-related activity. The patient could not visually detect objects before injections, regardless of goggle wear, or after injection without goggles. No intraocular inflammation was noted. 

    Limitations

    Larger studies and long-term data are needed to ascertain true clinical implications and assess safety and efficacy. This study reports on only a single patient because follow-up of other patients was limited due to COVID-19 restrictions.

    Clinical significance

    This is a remarkable landmark demonstration that provides proof of concept that optogenetic therapies have the potential to restore visual function to patients blinded by photoreceptor degeneration.