The road to visual prosthetics: a timeline

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Vision prosthetic technology has come a long way since the first experiments with optic cortex implants that began in the 1960s. Commercially available vision prostheses are available today, but they can only restore vision limited with low spatial resolution. Challenges such as biocompatibility or cost remain significant obstacles.

Recent research suggests that may be about to change – and we may be just one step away from highly sophisticated visual prosthetics.

1791, 1929, 1968-1982: First research on electricity and the visual cortex of the brain

The history of visual prostheses dates back to 1929. German neuroscientist Otfrid Foerster demonstrated that electrical stimulation of the visual cortex could lead to the subject’s perception of flashes of light – or “phosphenes”.

This research built on previous findings by scientists who first studied electrical stimulation of the nervous system, such as The discovery of Luigi Galvani in 1791 effects of electricity on animal tissues. However, experiments with visual prostheses did not begin until nearly 40 years after Foerster’s work.

In the mid-1960s, scientist Giles Brindley worked on a device which used an array of electrodes under the scalp to stimulate a subject’s occipital lobe – which contains the brain’s visual cortex. It could reliably produce phosphenes in the subject’s field of vision. Brindley, in conjunction with scientist WS Lewin, first performed human testing of the device in 1967.

The team published their findings in 1969 and continued their work on early visual prostheses in the 1980s, eventually working with blind patients. Brindley and Lewin found that they could stimulate these phosphenes using their device, even in totally blind patients.

1980s-2000s: continuous research and more sophisticated prototypes

Brindley’s work was continued by William H. Dobelle, a biomedical researcher also known for his work on respiratory stimulators. Dobelle’s experiments in the 1980s and 1990s led to the creation of “Dobelle’s eye”, a prosthesis that stimulates the brain’s visual cortex.

It consists of a pair of glasses attached to a camera, an ultrasonic range finder and a small computer. The computer processes information from the camera and rangefinder, then converts this information into a signal that is transmitted to an array of electrodes implanted in the visual cortex of the recipient.

The device allowed recipients to see the outlines of images and objects as a series of white dots on a black background.

By 2002, the continued development of visual prosthetic technology had produced a prosthesis that allowed an implant recipient, a former pilot named Jens, to drive a car in the Dobelle Institute parking lot.

Years 2010-2020: commercial viability and new challenges

Only one visual prosthesis has been approved for marketing by the FDA – the Argus II Retinal Prosthesis – also known as the Argus II Bionic Ocular System. The Argus II has also received EU CE marking, along with two other visual prostheses, the IRIS 2 (Pixium) and the Alpha-AMS (Retina Implant).

These devices can provide significant benefits to recipients – primarily limited vision restoration, allowing recipients to see light, motion, and shapes. This makes it easier for users to move around and work alone.

In addition to providing limited vision for blind device users, these prostheses can also help offset other challenges blind people may face. For example, people with physical disabilities are two to four times more likely experience a substance use disorder. Vision-restoring implants could help improve recipients’ quality of life and reduce the risk of addiction.

Obsolescence and other concerns

Commercial implants pose a new challenge: what happens when a manufacturer of visual prostheses goes bankrupt?

Bionic eye maker Second Sight, founded in 1998, was the maker of the Argus II retinal prosthesis. Due to financial issues, the company began phasing out this product in 2020. Implant recipients could no longer receive maintenance or repairs to their device. If it breaks down or gets damaged, it will be permanently non-functional, causing users to go blind.

Implant recipients describes the company’s technology as fantastic but criticized it for not providing support. Non-functioning implants have prevented recipients from receiving MRIs and can lead to medical complications. Denture removal is possible, but the process can be painful and expensive.

Several other bionic eye systems are currently being tested or awaiting approval. In the future, scientists, policymakers, and manufacturers of these devices may need to consider the potential consequences of discontinuing visual prostheses.

Related ethical concerns, such as the cost of purchasing and maintaining a bionic eye, will also likely become more important. Companies and scientists working with visual prostheses may have to consider action plans for people who cannot afford to buy or maintain a device.

2020 and beyond: The future of visual prosthetics

Existing visual prostheses can only provide limited restoration of the user’s vision, but future technology could completely reverse blindness.

The Gennaris bionic vision system, which was about to be start of human trials in 2020is an example that can provide more extensive view restoration.

Other bionic eye systems offering limited vision, such as the Argus II, IRIS 2 and Alpha-AMS systems, are also under development. These prostheses could become commercially available in the next few years, providing additional options for potential device wearers.

How visual prostheses can continue to grow

Modern visual prostheses are much more advanced than the original prosthetic devices developed by Lewin and Brindley. However, biomedical researchers still have a long way to go.

Existing bionic eyes cannot provide full vision restoration to users, although the limited vision they provide can be extremely valuable. This may offset some of the negative health effects – such as higher rates of substance abuse – associated with physical disabilities.

Bionic eyes that fully restore vision may be possible at some point. These eyes could transform the current market for visual aids, although users would continue to face certain risks, such as the possibility of a manufacturer going bankrupt.

The 2020s will likely be a major decade for the development of visual prosthetic technology. If full restoration of sight is possible, we could see human trials of new systems beginning to show results this decade.

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