The bionic eye returning vision to the blind

When the Bionic Woman premiered in the 1970’s it was considered sci-fi, an unlikely look at a future with unfathomable medical advances that could merge technology and the human body to cure injury and ailments. Today scientists at the Byers Eye Institute at Stanford have brought that concept to the present.

Groundbreaking results from a recent phase 3 clinical trial on a technology developed at Stanford, called the PRIMA retinal implant system, are offering hope for restored vision through cutting edge technology to patients who are legally blind.

The clinical trial focuses on those struggling with advanced dry age-related macular degeneration (AMD), also known as atrophic AMD, which is among the most common untreatable causes of blindness. The degenerative eye condition primarily affects older patients and causes photoreceptors (the cells that detect light) in the macula (the part of the retina responsible for central vision) to gradually break down. Eventually, reading, driving, and other tasks that require good eyesight can become impossible.

That’s where the PRIMA device can serve as an electronic replacement for the lost photoreceptors, and the recent clinical trial proves that it works. Daniel Palanker, PhD, professor of ophthalmology at the Byers Eye Institute at Stanford, developed the cutting-edge photovoltaic retinal prosthesis, which is currently the only treatment of its kind in the world that can restore such a measure of central vision in these patients.

By all accounts, the PRIMA implant is nothing less than revolutionary.

“Currently, it’s the only way to restore sight in AMD patients,” Palanker said. “People study drugs to slow down the progression of this disease, but if you have already lost the receptors and you’re blind in the center of the visual field, there’s nothing currently except for our implant.”

Three core components make up the PRIMA system: a tiny wireless implant placed under the retina, a pair of augmented-reality glasses with an integrated camera and projection module, and a pocket-sized computer that processes visual information.

Once everything is in place, a cascade of processes create visual perception in real time. First, the glasses capture a scene while the computer processes the image, and converts it into optical signals projected onto the implant under the retina. Then, photovoltaic cells in the implant convert light into electrical current, which activates the retina’s nerve cells, and sends information to the brain.

“Those photovoltaic pixels replace the dead photoreceptors,” said Mohajeet Bhuckory, PhD, a key researcher working on the trial. “The brain merges the prosthetic vision and the natural vision together and it appears as one continuous image.”

Following the implantation, patients attend special training sessions and wear augmented reality glasses that work in tandem with the PRIMA system. These glasses are essential for capturing and processing visual information and are a critical part of the post-implantation setup.

The patients enrolled in the phase 3 PRIMA trial had severe vision loss due to dry AMD with visual acuity of 20/400 or worse in their affected eye, rendering them legally blind. The results were remarkable: Though the participants still have far from perfect vision, a majority of patients regained what is known as “form vision,” the ability to read and write, recognize symbols and letters, and navigate their surroundings with more confidence — tasks many hadn’t been able to enjoy in years.

“People have tried electrical and optogenetic prosthetics for decades, since the early ‘90s, but these are the first really to provide form vision,” Palanker said. “Now, blind people can read from the page of a book or a journal, read signs in the subway, play cards, write, and more.”

Even more exciting is the next-generation PRIMA device being tested in the lab, which improves on the pixel density through innovations in the underlying engineering. With those advances, the next-generation version should be able to restore vision to a greater degree.

The results are not just encouraging to the doctors and scientists behind the PRIMA system, Bhuckory said. For many of the patients in the clinical trial, the technology has become a lifeline.

“Blindness is much more than a disease; it affects the patient’s autonomy and everyone around them and comes with high healthcare costs,” he said. “Such encouraging results with PRIMA devices point to a much better future.”