Scientists at EPFL (École Polytechnique Fédérale de Lausanne), a leading European scientific center, have developed a novel, non-invasive brain stimulation therapy that can significantly improve visual function in stroke patients suffering from hemianopsia (the loss of half of the visual field). This approach offers a much faster and more effective way to restore vision.
Every year, thousands of stroke survivors develop hemianopsia, which significantly hinders their daily activities such as reading, driving, or navigating in crowded places.
Currently, there are no reliable methods to treat hemianopsia that actually restore lost vision. Existing therapies mainly teach patients how to adapt to the vision loss, and sometimes require months of intense neurorehabilitation to achieve only minor improvements.
According to the researchers, the main challenge lies in the fact that stroke often damages the coordination between brain regions, for instance, between the primary visual cortex and the medial-temporal area (the motion-processing zone). These regions typically exchange information through precise electrical brain rhythms—oscillations. A stroke can disrupt this communication.
A team of researchers at EPFL’s Neuro-X Institute, led by Professor Friedhelm Hummel, has developed a new treatment method that combines visual training with multifocal, non-invasive brain stimulation to restore this “disconnected” communication and accelerate visual recovery.
The study shows that this new approach significantly enhances the recovery of visual functions, even in patients who have had visual impairment for a long time.
The essence of the method is based on cf-tACS technology. cf-tACS is a non-invasive brain stimulation technique that simultaneously uses two different electrical frequencies to improve the communication between different parts of the brain and their ability to process information. Using this technology, the researchers applied low-intensity electrical signals to two areas:
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First Area (Primary Visual Cortex): They delivered low-frequency Alpha waves.
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Second Area (Motion-Sensitive Medial-Temporal Area): They delivered high-frequency Gamma waves.
This method (using Alpha and Gamma waves) mimics the brain’s natural “bottom-up” flow of information, helping to restore the connections damaged by the stroke.
The use of cf-tACS, which simulates the natural flow of information in the brain, yielded significant results:
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Sharp Improvement: Patients who received this stimulation showed significantly greater improvements in motion perception and experienced an expansion of their visual field.
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Daily Benefits: Some patients reported real changes in their daily lives (e.g., being able to see things from a car that they couldn’t see before).
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Scientific Confirmation: The studies confirmed that the treatment restored communication between the two visual areas of the brain.
This method is a promising, fast, and accessible means of restoring vision lost after a stroke.
