Retinitis pigmentosa: New device restores usable vision

A team of researchers in Germany have created a retinal implant that has allowed three blind people who have Retinitis pigmentosa (RP) to see shapes and objects within days of the device being implanted.

The electronic visual prosthesis was developed by Retinal Implant AG, Germany and the Institute for Ophthalmic Research, University of Tuebingen, Germany. The researchers describe it as an “unprecedented advance in electronic visual prostheses”.

The device is a microchip carrying 1500 photosensitive diodes that slides into the retina where the photoreceptors would normally be.

“We have shown that people can be provided with enough useful vision for daily life,” said Professor Eberhart Zrenner, chairman of the Tuebingen Eye Hospital in Germany and director of the company that is developing the impant.

Miikka Terho from Finland, who was one of the three patients fitted with the temporary chip at a clinic in Germany, was subsequently able to discern a clock, household objects and letters.

Surgeons spent six hours operating on each of the three patients, first cutting a small flap in the delicate retina, and then inserting the chip, which measures 3mm by 3mm. The chip was connected via thin wire to a battery that each patient wore on a necklace. It contains 1,500 light-sensitive elements that replace the defunct cells in a blind patient’s retina.

Retinitis pigmentosa is a group of genetic eye conditions that leads to incurable blindness. Progression of Retinitis pigmentosa differs with each case, the worst being complete blindness as early as childhood, to being legally blind around age 40 or 50 with some retention of sight for life. Those affected usually experience nyctalopia, (night blindness), followed by peripheral vision reduction (tunnel vision) and then loss of central vision over several years or decades. The main risk factor for Retinitis pigmentosa is family history. The main sign of the disease is the presence of dark deposits in the retina.