The Clinically Blind See Again With an Implant the Size of a Grain of Salt

Seeing is believing. Our perception of the world heavily relies on vision. What we see depends on cells in the retina, which sit behind the eyes. These delicate cells transform light into electrical pulses that go to the brain for further processing.

As people age or due to disease or genetics, retinal cells often break down. One significant condition, geographic atrophy, gradually destroys retinal cells, making it challenging for individuals to focus on text, recognize faces, or discern colors and textures in low-light situations. This condition especially affects central vision, vital for focusing on specific objects.

The outcome is akin to viewing the world through a blurry lens. Walking down a dimly lit street becomes disorienting, and everyday activities such as reading a book or watching a movie turn into challenges rather than sources of enjoyment. Regenerating the retina poses substantial difficulties, and the demand for transplant donors remains unmet.

In an effort to address these issues, a small clinical trial may offer hope. Led by a pioneering company headquartered in Alameda, California, the study involved implanting a tiny chip that serves as a replacement for the retina in 38 participants who were legally blind.

Dubbed the Prima system, these volunteers wore custom-designed eyewear equipped with a camera that acted as a “digital eye.” The camera captured images which were then transmitted to the implanted artificial retina, enabling it to convert the visual data into electrical signals for the brain to interpret.

Preliminary results indicate an improvement in the participants’ ability to read the eye exam scale—a common test that involves reading random letters with progressively smaller sizes. Notably, some participants could read in low-light conditions at home, utilizing the camera's “zoom-and-enhance” feature.

The trial is ongoing, with final results anticipated in 2026—three years following the implant. Frank Holz, scientific coordinator at the University of Bonn Ernst-Abbe-Strasse in Germany, noted, “The results are a milestone for geographic atrophy resulting from age. Prior to this, there have been no real treatment options for these patients,” he stated in a press release.

Max Hodak, CEO of Science Corp and former president of Elon Musk’s Neuralink, emphasized the significance of the trial, saying, “To my knowledge, this is the first time that restoration of the ability to fluently read has ever been definitively shown in blind patients.”

Eyes Wide Open

The eye is a biological marvel, with its various layers acting as lenses that focus light onto the retina—the eye’s visual sensor. The retina consists of two types of light-sensitive cells: rods and cones.

The rods are primarily located at the outer edges of the retina, allowing for visibility of shapes and shadows in dim lighting or peripheral perspectives. However, rods do not detect color or sharpen focus, contributing to their blurriness during night vision. Additionally, rods efficiently capture rapid movements at the edges of sight.

Cones are predominantly situated in the center of the retina and play a critical role in detecting vibrant colors and sharply focusing on specific details, such as text. Both cell types depend on supportive cells that provide the structural integrity of the retina—akin to soil nourishing a garden.

With age, these retinal cells can deteriorate, potentially resulting in age-related macular degeneration and subsequent loss of central vision, a common condition affecting nearly 1.8 million Americans. Deterioration leads to visual distortions; straight lines may appear crooked, and colors seem dim, especially in low-light scenarios. The later stages, known as geographic atrophy, result in legal blindness.

Scientists have sought treatments for years. One promising avenue involves using autologous stem cells derived from a patient’s blood to create healthy retinal support cells. Medical professionals can transplant these cells, integrated with a biodegradable scaffold, into the eye. Initial studies have shown this patch can integrate with the retina and, in some cases, reverse the disease. However, custom tailoring for each patient requires an extensive timeframe of up to six months, making scalability challenging.

A New Vision

The Prima system offers a novel approach that circumvents biological regeneration by implementing a wireless microchip that compensates for parts of the retina. The implant, measuring approximately two millimeters square—similar to the size of a grain of salt—is surgically inserted beneath the retina. According to the manufacturer, the entire procedure lasts only 80 minutes, which is less than the average length of a feature film.

Each chip utilizes light-sensitive pixels that convert light patterns into electrical pulses that the brain can interpret. Accompanying the chip is a specially designed pair of glasses embedded with a camera that captures visual data and transmits it to the implant using infrared signals.

Together, the components mimic the functionality of natural eyes. Images captured by the camera are relayed to the artificial retina, where they undergo conversion into electrical signals for processing by the brain.

Initial outcomes from the trial are encouraging. According to reports, participants exhibited improved visual acuity one year post-implantation. Many who initially ranked as legally blind—averaging a vision score of 20/450—experienced enhancement, moving toward a normal vision score of 20/20. When put to an eye exam test, participants improved their ability to read approximately 23 additional letters, or about five more lines, on the chart compared to baseline results. One patient notably increased their letter recognition by 59 letters, equating to over 11 lines of improvement.

The Prima implant has positively influenced daily functions. Participants have reported being able to read, play cards, and solve crossword puzzles—activities that necessitate central vision.

However, the system is not universally effective. Some participants reported significant side effects, including minor retinal tears, which primarily resolved, according to the company. Additional cases involved blood leaks beneath the retina, addressed promptly by medical professionals; specifics regarding the injuries and their management remain scant.

The trial will continue for an extended period, during which participants will be monitored for three years to assess long-term enhancements and track potential side effects. The research team also aims to evaluate quality of life pertaining to vision-related activities and mental health.

Hodak remarked that the trial “represents an enormous turning point for the field, and we’re incredibly excited to bring this important technology to market over the next few years.”

Image Credit: Singularity Hub

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