A tiny eye chip developed by Stanford University helps blind people see again

With the help of digital features such as adjustable magnification and enhanced contrast, some participants achieved visual acuity comparable to 20/42 vision.

The study results were published October 20 in the journal New England Journal of Medicine.

A milestone in restoring functional vision

The implant, named PRIMA and developed at Stanford Medicine, is the first artificial eye device to restore usable vision to individuals with irreversible vision loss. This technology allows patients to recognize shapes and patterns, a level of vision known as pattern vision.

“All previous attempts to provide vision using prosthetic devices have essentially led to photosensitivity, not actually to vision,” said Daniel Palanker, MD, professor of ophthalmology and co-senior author on the paper. “We are the first to provide a vision of the model.”

The research was co-led by José Alan Sahil, MD, professor of ophthalmology at the University of Pittsburgh School of Medicine, with Frank Holz, MD, of the University of Bonn in Germany, as lead author.

How does the Prima system work?

The system consists of two main parts: a small camera attached to a pair of glasses and a wireless chip implanted in the retina. The camera captures visual information and projects it through infrared light to the implant, which converts it into electrical signals. These signals replace damaged photoreceptors that normally detect light and send visual data to the brain.

Project Prima represents decades of scientific effort, which includes numerous prototypes, animal tests, and initial human trials.

Palanker first came up with the idea two decades ago while working with ocular lasers to treat eye disorders. “I realized that we should use the fact that the eye is transparent and communicate information through light,” he said.

“The device we imagined in 2005 now works very well in patients.”

Replace missing photoreceptors

The participants in the latest trial were suffering from an advanced stage of age-related macular degeneration known as geographic atrophy, which gradually destroys central vision. This condition affects more than 5 million people worldwide and is the leading cause of irreversible blindness among older people.

In macular degeneration, light-sensitive photoreceptor cells in the central retina degenerate, leaving only limited peripheral vision. However, many of the neurons in the retina that process visual information remain intact, and Prima takes advantage of these surviving structures.

The implant, which is only 2 x 2 mm in size, is placed in the area of ​​the retina where photoreceptors have been lost. Unlike natural photoreceptors that respond to visible light, the chip detects infrared light emitted by the glasses.

“The display is done by infrared light because we want to make sure it is not visible to the remaining photoreceptors outside the implant,” Palanker said.

Combining natural and artificial vision

This design allows patients to use their natural peripheral vision and new artificial central vision simultaneously, improving their ability to orient themselves and move.

“The fact that they see synthetic and peripheral vision simultaneously is important because they can integrate vision and use it to the fullest,” Palanker said.

Because the implant is photovoltaic — relying solely on light to generate an electrical current — it operates wirelessly and can be safely placed under the retina. Previous versions of prosthetic eye devices required external power supplies and cables extending outside the eye.

Read again

The new trial included 38 patients over the age of 60 with geographic atrophy due to age-related macular degeneration and vision worse than 20/320 in at least one eye.

Four to five weeks after the chip was implanted in one eye, patients began using glasses. Although some patients were able to distinguish patterns immediately, all patients’ visual acuity improved over months of training.

“It may take several months of training to reach peak performance — similar to what a cochlear implant requires to master artificial hearing,” Palanker said.

Of the 32 patients who completed the one-year trial, 27 were able to read and 26 showed a clinically meaningful improvement in visual acuity, which was defined as the ability to read at least two additional lines on a standard eye chart. On average, participants’ visual acuity improved by 5 lines; One was improved by 12 lines.

The participants used the prosthetic in their daily lives to read books, food labels and subway signs. The glasses allowed them to adjust contrast, brightness, and magnification up to 12 times. Two-thirds of participants reported moderate to high satisfaction with the device.

Nineteen participants experienced side effects, including ocular hypertension (high pressure in the eye), peripheral retinal tears, and subretinal hemorrhage (blood pooling under the retina). None were life-threatening, and almost all resolved within 2 months.

Future visions

Currently, the PRIMA device provides black-and-white viewing only, with no shadows in between, but Palanker is developing software that will soon enable the full range of grayscale.

“Reading is number one on patients’ wish lists, but second place, which is very close, is facial recognition,” he said. “And face recognition requires grayscale.”

He also specializes in designing engineered chips that will provide higher-resolution vision. Resolution is limited by the size of the pixels on the chip. Currently, pixels are 100 microns wide, with 378 pixels per chip. The new version, which has already been tested on mice, may contain pixels as small as 20 microns across, with 10,000 pixels on each chip.

Palanker also wants to test the device for other types of blindness caused by loss of photoreceptors.

“This is the first version of the chip, and the resolution is relatively low,” he said. “The next generation of chip, with smaller pixels, will have better resolution and will be paired with more stylish glasses.”

A chip with 20 micron pixels could give a patient 20/80 vision, Palanker said. “But with electronic zoom, they can get close to 20/20.”

Researchers from the University of Bonn, Germany; A Foundation Hospital de Rothschild, France; Moorfields Eye Hospital and University College London; Academic Teaching Hospital Ludwigshafen; University of Rome Tor Vergata; Medical Center Schleswig-Holstein, University of Lübeck; Croix-Rousse University Hospital and Claude Bernard Lyon University 1; Azienda Ospedalera San Giovanni Addolorata; Monticelli Paradise Center and Aix-Marseille University; The Inter-Community Hospital of Créteil and the Henri Mondor Hospital; Kanapsheft Sar Hospital; University of Nantes; University Eye Hospital Tübingen; University Medical Center Münster. Purdue University Hospital. National Hospital 15-20; Erasmus University Medical Centre. University of Ulm; Science Company. University of California, San Francisco; University of Washington; University of Pittsburgh School of Medicine; Sorbonne University contributed to the study.

The study was supported by funding from Science Corp, the National Institute for Health and Care Research, Moorfields Eye Hospital NHS Foundation Trust and University College London Institute of Ophthalmology.