Optogenetic tools have officially changed the fight against blindness

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Patients diagnosed with degenerative eye disorders, such as retinitis pigmentosa (RP) or choroideremia, face a gradual loss of light-sensing cells that eventually leads to blindness. Historically, most treatments could only aim to slow disease progression; however, bioengineering is changing toolkits, allowing scientists and doctors to do more. Optogenetics is an excellent example of this, and it has already ushered in a paradigm shift: Clinicians are being empowered to aim for stem cell-free restoration of vision, rather than degenerative delay.

If this sounds familiar, maybe you remember my top pick in the Spring 2025 edition of Regenerative Medicine News Under the Microscope. I’ve also covered this story on my YouTube channel. However, there have since been both significant progress and shifts in the competitive landscape, with another major player emerging in the race to restore functional vision using optogenetics.

The tool

To recap: Optogenetic tools enable us to engineer cells and molecules so that aspects of their activity can be controlled using pulses of light. In the case of vision repair, a gene encoding a light-sensitive protein, called an opsin, is virally delivered directly into the neurons of the eye, which weren’t otherwise photosensing themselves. Because these neurons are already patched into the central nervous system (CNS), once they’re equipped with opsins, they can transmit light-related signals to the brain and reproduce aspects of vision.

Crucially, the described approach is “mutation-agnostic.” There are over 100 known genes and more than 1,000 corresponding mutations that can contribute to RP alone, meaning that traditional corrective or compensatory gene therapy would require a customized treatment for each genetic anomaly. Such an approach would represent greater cost and complexity. Optogenetics bypasses this problem entirely, making it a viable treatment for many forms of retinal blindness without requiring genetic testing per se.

Currently, two companies – Nanoscope Therapeutics and Ray Therapeutics – are leading the clinical translation of this technology. While both use optogenetics, their opsins of choice differ, as does their progress.

The frontrunner

Nanoscope Therapeutics (the team I’ve highlighted previously) is developing a therapy called MCO-010 (also known as vMCO-I in early trials, now branded as MOGENRY). MCO stands for multi-characteristic opsin (MCO), representative of their unique approach to the problem. Their opsin is a synthetic, broad-spectrum actuator that even works well in low-light conditions. It was designed to incorporate three different protein domains that each respond to a different wavelength of light (one for red, one for blue and one for green). Why is this a critical advance? Opsins typically respond to just a single wavelength, which is among the reasons why they are less sensitive and need more light to work. Previous attempts to use single-wavelength opsins to restore human vision have required wearable devices that amplify light inputs. While that work was pioneering and represented a significant milestone, the ability to see without external technological aid is the ideal outcome of new therapies. Nanoscope’s MCO is thus an exciting innovation in the field.

MCO-010 is delivered via a single, in-office intravitreal injection and targets the highly dense bipolar neurons in the retina. These cells are signalled by photoreceptors under healthy circumstances, but since the photoreceptors are degenerating in disease contexts, direct targeting of the second-line bipolar cells offers a solid workaround. Newly light-sensing bipolar cells can now transmit information to their neighbours (ganglion cells), which in turn signal the brain.

Nanoscope had previously completed a a Phase I/IIa open-label, dose-escalation study that evaluated two doses in 11 patients with advanced RP. Those data are published here. According to Nanoscope, the treatment was found to be safe and well-tolerated over five years of monitoring, with no serious adverse effects. They’ve also completed a Phase IIb/III RP study since I last reported on their progress, though those data have not yet been peer reviewed. The new study had 27 patients enrolled, according to the clinical trial record, despite initial intentions to look at just 18 subjects at two doses. Frankly, I thought it was amazing to see their patients (no pun intended) go from being completely unable to detect a designated light source before treatment, to being able to walk straight towards it post-treatment. The company currently considers its therapy to be registration-ready for RP and Phase III-ready for Stargardt disease (with their Phase II data for this indication published here).

A new player emerges

Another company looks to be a serious competitor in this space. Ray Therapeutics is now firmly in the race, with investors betting big on their efforts.

Ray’s lead candidate, RTx-015, utilizes ChRown opsins; these are improved channelrhodopsin variants, referred to as CoChRs. The team has bioengineered the protein to further increase its light sensitivity, though their approach was different than Nanoscope’s MCO, as ChRown still appears to be a single-wavelength opsin. Despite this, Ray reports that ambient lighting conditions are sufficient for activation without the use of amplifying goggles. Again, this offers a major advantage over original technologies in this space. I’ve not seen preclinical data published explicitly under the Ray Therapeutics banner, but they often cite this paper as foundational for their venture, and Dr. Zhuo-Hua Pan is listed both as an author on the paper and as an inventor on Ray Therapeutics’ major patent. Their data were also presented in a webinar through the Choroideremia Research Foundation’s series on YouTube. The talk was delivered by Dr. Raj Agrawal, Vice President, Clinical Development & Therapeutic Area Head.

Like MCO-010, RTx-015 is designed as a one-time intravitreal gene therapy that aims to provide lifelong benefits. Ray Therapeutics is currently running its Phase I trial, evaluating up to four dose cohorts of RTx-015 in approximately 18 patients with either RP or choroideremia. They’ve enrolled 10 patients so far. Instead of delivering their gene to bipolar neurons, however, they are targeting ganglion cells – the next link in the visual chain.

The scientific and regulatory community is showing strong support for Ray’s approach. Investors have rallied behind them, recently closing a US$125 million Series B financing round. Furthermore, the therapy has secured a Priority Medicines (PRIME) designation from the European Medicines Agency (EMA), complementing its existing Regenerative Medicine Advanced Therapy (RMAT) designation from the U.S. Food and Drug Administration (FDA).

Outlook

Optogenetics for vision restoration is a rapidly advancing field with several companies vying for leadership, but Nanoscope Therapeutics and Ray Therapeutics have emerged as the most compelling frontrunners in my view. Nanoscope leads the pack overall with statistically significant Phase IIb/III results and a Biologics License Application submitted to the FDA, making them the closest to regulatory approval relative to their competitors.

Furthermore, both teams have diversified their strategies. Ray Therapeutics is pursuing both ganglion cell (RTX-015) and bipolar cell (RTX-021, pre-clinical) targets, while Nanoscope Therapeutics is looking at both viral (MCO-010) and non-viral (MCO-020, pre-clinical) opsin delivery approaches.

Notably, GenSight was the scientific first-mover, widely considered a trailblazer in the field. However, their candidate requires the light-amplifying goggles that I mentioned earlier. This strategy probably won’t win out with patients (and therefore, investors). It will likely be adapt-or-fall behind for optogenetic tools relying on external devices.

There are currently other companies with similar offerings at various stages of clinical development, but none are as active or as advanced along their R&D pipelines just yet.

I’ve put together a table comparing the two leaders in this space:

Both Nanoscope Therapeutics and Ray Therapeutics represent a major leap forward in treating late-stage degenerative eye diseases. By utilizing mutation-agnostic optogenetics, these single-injection therapies avoid the complexities of traditional gene editing to restore functional vision.

Whether or not these technologies will eventually lead to full vision restoration remains an important open question in the field right now. How far will optogenetic tools take us? Will they ever be able to reproduce native vision as research and development continue? Time will tell.

I’m very excited to see how this landscape continues to change!

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Lyla El-Fayomi

Dr. Lyla El-Fayomi has a PhD in Molecular Genetics from the University of Toronto. She is a researcher and freelance science writer headquartered in the Greater Toronto Area. Follow her on X @DrLylaElFay

Latest posts by Lyla El-Fayomi (see all)

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