Fine-tuning retinal implants

Today’s retinal implants ‘overstimulate the retina,’ compared to the natural activation of photoreceptors

31 Aug 2016 by Olivia Wannan

The technology for a retinal implant capable of allowing a patient to recognise a face may now be possible.

Scientists used retinal prostheses in rodents to compare how the same visual stimulus activated the brains of this group versus the brains of normal-sighted animals.

They discovered that the implants activated the right area of the visual part of the brain, but that the activation was “much too great.”

The French researchers attribute this over-activation of the brain back to the interface of the implant and the retina. The devices stimulate not only the right nerve cells, but a number of the neighbouring cells as well.

This knowledge allowed the team to work with specialists in interface physics to re-design the device where it connects to the retina. The work, published in the journal eLife, resulted in an implant that activates the brain of rodents in a pattern that is more like animals with natural vision.

Researcher and Aix-Marseille University neuroscientist, Dr Frederic Chavane, told OT that the next step was to make sure that the technique worked in animals beyond rodents.

He explained: “We need to make sure that it works on a retinal tissue that is closer to human, such as in non-human primates … We could imagine implanting non-human primates and make behavioural tests to demonstrate the generalisation of our method.”

Dr Chavane added: “We then need to have access to the electronics of the implanted retinal prostheses currently on the market in order to characterise the electrical properties of the prostheses.”

However, he emphasised that, despite there being more work to be done, the study has opened the way towards making promising improvements in retinal implant technology for human patients.

Image credit: Allan Ajifo


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