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Retinal microchip provides slight hope

Is there a slight chance that patients suffering from Retinitis pigmentosa, or even from age-related macular degeneration, might be able to regain their vision? A microchip implanted beneath the human retina might at least give such patients the ability to make out the outlines of objects. The chip was developed by an Ulm researcher in a BMBF-funded cooperative research project.

Retinitis pigmentosa is an inherited or acquired disease of the retina in which defective photoreceptors of the retina lead to progressive visual loss. Age-related macular degeneration is the major cause of visual impairment and blindness in elderly people in industrial countries. According to experts, there are about two million people in Germany who suffer from such disorders. The most important sensory cells of the eye are located in the macula, an area of the retina approximately 1.5 mm in size. The macula enables people to see clearly.

South German research alliance

Rothermel speaking in San Francisco.
Together with eye doctors from the Regensburg University Hospital, researchers from the University Eye Hospital in Tübingen are focusing on the medical part of the project that is receiving funding of 1.3 million euros. The chip was developed by a team of researchers at the University of Ulm, led by Albrecht Rothermel of the Institute of General Electrotechnology and Microelectronics on behalf of the Reutlingen-based medical technology company Retina Implant AG.

Last year, the coordinator of the project, Professor Eberhard Zrenner from the University Hospital in Tübingen, was able to report on the group’s initial results. Some of the seven patients implanted with the microchip from an institute in Stuttgart were able to see the outline of objects or could localise light sources.

The project partners hope that the next generation of the new microchip (3 x 3 mm) developed at Ulm University will deliver even better results. “If everything goes to plan, the first chips will be implanted this year,” said Rothermel who recently presented the project at the ISSCC in Francisco, which is the world’s most important conference on electronic circuits.

Recognising finer structures

Hope from Ulm – the retinal chip. (Photo: University of Ulm)
Rothermel expects that the new chip will have a better resolution. “We hope that the patients will be able to discern finer structures,” said Rothermel who at the same time warns against exaggerated expectations since it is difficult to place the chip in the area of the retina where clearest vision is possible. However, the scientist from Ulm expects that the new chips will have a longer lifetime than the previous ones.

Rothermel explained that the new version of the chip no longer requires the patients to be connected up to measurement devices. Instead, they will be implanted with a small container below the skin that transmits the data by way of induction. “The patients will then be able to go home,” said Rothermel.

Recording and transmitting visual stimuli

The microchip is produced by an Austrian company based on a design developed by Rothermel. These electronic circuits combine the experience from the first series of investigations with the skills of the Ulm researchers.

The artificial visual aids take on the tasks of the retina that can no longer be done by the defective photoreceptors: detecting visual stimuli and transmitting them to the visual nerves that will then process the stimuli and transmit them to the brain. The visual stimuli are received by 1600 photosensors and titanium-nitride electrodes of the microchip. Independently of the incidence of light, the sensors control the electrodes with electronic circuits that transfer the signals as electric tension to the visual nerves.

Chip relies on intact visual nerves

However, in order for the system to function and potentially reach Zrenner’s long-term objective of six-percent visual acuity, the visual nerves have to be intact. In such cases, the patients implanted with the chip might be able to recognise faces or read with strong glasses. The artificial retina replacement is not a remedy for inherited blindness, damage to the visual centre in the brain or for late-stage glaucoma.

Strong international competition

Zrenner’s project and his partners from Ulm are competing against several teams across the globe. According to “Science” there are about 24 teams of researchers who are focusing on the development of retinal chips, sometimes with considerably higher budgets and using other scientific approaches. At present, there are two German and two American chips as well as one Japanese chip that are ready for testing. Rothermel is confident: “I think our solution has a good chance of being successful.”

Source: University of Ulm, 4.3.2008 (wp, 12.3.2008)
Further information:
Prof. Dr. Albrecht Rothermel
Tel.: +49 (0)731/50-26204
Website address: https://www.gesundheitsindustrie-bw.de/en/article/news/retinal-microchip-provides-slight-hope