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Photoswitchable eye drops restore light sensitivity in blind animals

Photoswitchable eye drops restore light sensitivity in blind animals

New Capabilities

Barcelona-led team's light-activated compounds bypass dead photoreceptors without surgery, implants, or gene therapy

Today: Eye-drop delivery path highlighted

Overview

Updated 1 hour ago

Blind mice given a new eye drop regained an instinct they had lost: avoiding bright areas. The drug, called prosthe6, restored light perception in animal models of age-related macular degeneration and retinitis pigmentosa within hours of a single dose. The treated mice avoided bright zones at light levels comparable to indoor lighting or a cloudy day.

Prosthe6 is a photoswitchable small molecule. It attaches to metabotropic glutamate 6 receptors on ON bipolar cells, the neurons that relay photoreceptor signals deeper into the retina. When photoreceptors die, these cells stay intact. The drug lets them sense light directly, turning on in the dark and off in ambient white light.

Why it matters

If prosthe6 reaches humans, millions with advanced macular degeneration or retinitis pigmentosa could regain functional vision without surgery, gene therapy, implants, or specialized equipment.

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Key Indicators

2
Compounds that restored vision as eye drops
prosthe6-12 and prosthe6-15 restored light-avoidance behavior when applied topically, not injected.
10+ years
Duration of the research program
Photoswitchable molecule research ran across multiple Spanish universities and research institutions.
Nanomolar
Drug potency in vitro
Prosthe6 compounds show full efficacy at nanomolar concentrations with fast deactivation in light.
Phase 2
Stage of nearest competing therapy
Kiora Pharmaceuticals' KIO-301, a photoswitch targeting a different protein, is in a phase 2 trial for retinitis pigmentosa.

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People Involved

Organizations Involved

Timeline

January 2016 September 2026

3 events Latest: Today
  1. Eye-drop delivery path highlighted

    Today Coverage

    Optimist Daily features prosthe6 as a simpler alternative to gene therapy and implants, emphasizing the two compounds that work as ordinary eye drops.

  2. Prosthe6 results published in JACS

    Publication

    Consortium reports restored light avoidance in blind mice and saccadic eye movements in blinded zebrafish. Two compounds work as eye drops.

  3. Research program begins

    Origins

    IBEC and partner Spanish institutions begin developing photoswitchable molecules for vision restoration.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

2010-2020

Optogenetics for vision restoration (2010s)

Researchers spent a decade developing optogenetic approaches that deliver light-sensitive proteins to surviving retinal cells via gene therapy. Early human trials began in the late 2010s.

Then

Animal studies showed restored light sensitivity, but human trials required gene delivery and often high-intensity light.

Now

The approach proved the concept that inner retinal neurons can substitute for photoreceptors, but the genetic delivery mechanism added complexity and risk.

Why this matters now

Prosthe6 achieves the same goal as optogenetics without genetic manipulation—the drug is simply applied as drops and is reversible.

February 2013

Argus II retinal prosthesis (2013)

The FDA approved Argus II, the first retinal prosthesis, for adults with advanced retinitis pigmentosa. The device required surgical implantation of a 60-electrode array on the retina plus a camera on eyeglasses.

Then

Patients could detect light and identify large shapes, but resolution remained very limited.

Now

The device demonstrated that restoring some vision is possible without intact photoreceptors, but its invasiveness and cost restricted adoption.

Why this matters now

Prosthe6 aims to achieve what Argus II did with a drug instead of surgery, at a fraction of the complexity.

December 2017

Luxturna gene therapy approval (2017)

The FDA approved Luxturna, the first gene therapy for an inherited retinal disease. It delivers a working RPE65 gene to retinal cells, restoring vision in patients with that specific mutation.

Then

Patients with RPE65 mutations gained meaningful vision, often for years.

Now

The treatment only works for the small fraction of retinitis pigmentosa patients with RPE65 mutations, and requires surgery and permanent genetic modification.

Why this matters now

Prosthe6's key advantage is mechanism independence—it works regardless of which mutation killed the photoreceptors, reaching patients gene therapy cannot.

Sources

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