Artificial Retina Helps Restore Functional Sight

A novel electronic retinal prosthesis aids patients blinded by retinitis pigmentosa (RP) recover part of their lost sight.

The Alpha IMS is a light-sensitive subretinal microchip consisting of a 3x3-mm2 microchip with 1,500 electrodes implanted beneath the retina in the macular region, replacing photoreceptors lost due to RP. The microchip detects images with photodiodes and communicates the information electrically to nerve cells in the retina, requiring no externally visible gear. Each of the electrodes represents a pixel cell, containing a light-sensitive photodiode, a logarithmic differential amplifier, and a 50×50 μm iridium electrode into which the electrical stimuli at the retina are guided.


The microchip is positioned on a thin, highly flexible circuit board of polyimide with gold circuits connected in turn to a thin, coiled cable through which the electricity of the chip is supplied. This elastic cable passes through the orbital cavity to the bone of the temple and from there to a point behind the ear, where it is connected to an inductive power supply unit in a ceramic housing. A complementary metal-oxide-semiconductor (CMOS) camera chip rests on a polyimide carrier, and is connected via a silicone cable to a wireless power receiver.

The placement of the implant beneath the fovea allows patients to recognize objects and facial expressions, as well as read words and see dots on a pair of dice. The implant is based on the fact that in RP, a large part of the retina remains functional even after loss of sight. Although the rods and cones that normally convert light into nerve signals are destroyed by this disease, most of the retinal nerve tissue, which has the task of preprocessing information on its way to the brain, remains intact. The Alpha IMS is a product of Retina Implant (Reutlingen, Germany), and has received the European Union CE mark of approval.

“We are delighted that our subretinal implant has received CE marking, validating the safety and potential benefits of our revolutionary product to patients and physicians,” said Walter-G Wrobel, PhD, CEO of Retina Implant. “We look forward to working with clinicians across Europe interested in offering their patients a new pathway to regain vision. We also want to thank all of the patients who participated in our clinical trials, as without their contributions, this day would not be possible.”

“After more than seven years of rigorous testing in 36 patients, we are pleased to have demonstrated the safety, reliability and tolerability of the Alpha IMS,” added Prof. Eberhart Zrenner, MD, founding director of the Institute for Ophthalmic Research at the University of Tuebingen (Germany), who coordinated the clinical trial. “It was a very rewarding and touching experience to see blind patients regain some vision that helped them to better master the activities of daily life. This is a landmark in our journey to address the needs of the RP patient community which has limited treatment options available.”

Related Links:
Retina Implant
University of Tuebingen