Visual Cortex Stimulation Leads to Unexpected Natural Vision Recovery in Blind Patient

A clinical trial involving electrical microstimulation of the visual cortex resulted in the unexpected partial restoration of natural vision for a patient who had been blind due to irreversible optic nerve damage for over three years. The development, documented in the journal Brain Communications, challenges existing understandings of adult neuroplasticity following severe visual system trauma.

The research, conducted by personnel from CIBER (CIBER-BBN) and the Miguel Hernández University of Elche (UMH) in Alicante, Spain, primarily sought to evaluate a cortical visual prosthesis. Principal investigator Dr. Eduardo Fernández Jover, director of UMH's Institute of Bioengineering, confirmed the study's initial objective was to generate artificial visual perceptions, known as phosphenes, via direct electrical stimulation of the visual processing center, not to restore natural sight.

The volunteer, who suffered from bilateral anterior ischemic optic neuropathy—a condition stemming from insufficient blood flow to the optic nerve—received an intracortical microelectrode array containing 100 microelectrodes surgically placed into the primary visual cortex. Just two days after the procedure, while still hospitalized, the participant reported perceiving lights and distinguishing moving shadows, an unanticipated return of natural sight.

This visual improvement proved to be spontaneous and sustained, persisting even after the intracortical implant was surgically removed. The patient demonstrated the ability to describe the position of researchers' arms, indicating functional improvement in spatial awareness. Following the initial perception of light and motion, the patient engaged in a rigorous daily visual training regimen for at least half an hour, focusing on light perception, motion direction, spatial localization, and tracking shapes and letters.

Scientists suggest this combination of microstimulation and intensive, daily cognitive training was key to the observed effect. Although the patient's visual acuity slightly diminished over time, the overall achievement is considered a technical success, with visual evoked potentials registering clearly and intensifying throughout the experimental period. The sustained perception of visual information, even without the physical device, implies that the adult brain demonstrated a greater capacity for recovery than previously accounted for following prolonged optic nerve injury.

This finding offers a significant avenue for future therapeutic strategies aimed at activating residual vision, potentially through non-surgical modalities based on these neurostimulation principles. The study was conducted in collaboration with IMED Elche Hospital.