A step closer to a visual prosthesis

A research group from the University of Fribourg in Switzerland, China and the USA has made a discovery that could form the basis of a new generation of visual prostheses. They have demonstrated that small mammals, known as tupaias, are able to ’see’ even when their retina is not stimulated. To achieve this, the neurons in these animals were activated by light pulses, generating visual perceptions in their brains.

Activations of the visual system are normally generated by stimulation of the eye’s retina. The interdisciplinary research team, led by Professor Gregor Rainer of the University of Freiburg, has succeeded in technically producing such activations without any visual information reaching the eye, by stimulating appropriate neurons. Using the optogenetic method, which involves introducing transmembrane proteins into brain neurons, these were stimulated by pulses of light.

When the brain can see without the eyes

In principle, this method makes it possible to inject information into the visual system, even in cases of functional loss of the eyes, which the brain then interprets as vision. The results obtained could therefore form the basis of a future generation of visual prostheses. Further targeted research is required to make this a reality.

The visual prostheses currently available work inside the eye. While they may be useful for certain eye diseases, they have not yet achieved any real breakthroughs. The present work focuses not on the eye, but on the visual thalamus, the relay zone in the center of the brain that collects and transmits information from the eyes. Further fundamental research is now needed to ensure that these artificially created perceptions in the visual system reproduce natural vision as faithfully as possible.

The animal model as a basis for gaining new insights into a global problem

The tupaia’s developed visual system, similar to that of humans, makes it ideally suited to this study. Switzerland’s strict animal experimentation standards guarantee animal-friendly conditions.

According to an estimate by the World Health Organization, at least 2.2 billion people worldwide are visually impaired at near or distance. Most of those suffering from visual impairment or blindness are over the age of 50. It is to be hoped that further research in this field will lead in the medium term to the development and testing of innovative visual prostheses. Such a breakthrough would improve the quality of life for many people, particularly in societies with an ageing population.