Photoswitchable Prosthe6 Compounds Restore Optokinetic Reflex in Blind Zebrafish via Eye Drops

The consortium synthesized prosthe6 molecules incorporating azobenzene switches that isomerize under visible light, activating endogenous retinal circuitry downstream of lost photoreceptors. Delivery as eye drops or injection bypassed the need for viral vectors or electrode arrays used in current optogenetic and prosthetic approaches. In zebrafish larvae with induced photoreceptor degeneration, treated animals regained measurable saccadic eye movements in optokinetic reflex assays, demonstrating functional signal restoration at physiological light levels.

This approach directly addresses the 200 million people affected by AMD and RP by reactivating surviving inner-retinal neurons rather than replacing cells or genes. It builds on a decade of photopharmacology work at IBEC, UAH, and IQAC-CSIC, extending prior safety data from light-responsive drugs into a non-invasive format. Economic modeling in the paper links restored vision to reduced global productivity losses exceeding $400 billion annually.

Remaining hurdles include scaling efficacy to mammalian retinas and confirming long-term stability of the switch under repeated light exposure. The next logical step is a well-powered rodent study measuring visual acuity thresholds before any human dose-escalation trial.