Age-related macular degeneration (AMD) is a common eye disorder characterized by a loss of central vision, which results in blurred vision and blind spots. It is estimated that 200 million people have AMD worldwide, with those over 50 most affected by this irreversible medical condition.
Over 200 million people have AMD worldwide, and this statistic is expected to rise to 288 million by the year 2040.
A retinal implant helps restore vision by converting light from external surroundings into electrical impulses required by the brain to generate sight.
The CE and FDA-approved retinal implants such as the Argus II, Alpha-IMS, and IRIS II are commercially available for people with severe retinal degeneration.
Age-related macular degeneration was recently reported as the leading cause of permanent loss of sight in the adult population. Researchers at Stanford University have since sought a solution to this pressing problem by designing a retinal implant that can restore vision. This innovation holds hope for a better future for those affected by AMD.
Design and function of retinal prosthesis
The innovative retinal prosthesis designed by Professor Daniel Pallanker and his colleagues comprises two main pieces:
- Sunglasses using augmented reality.
- Small (roughly 2 mm) implant made of specialized pixels.
The process of restoring vision begins with a delicate surgery where the small implant is carefully aligned with the degenerated part of the retina. Those sunglasses capture external light from the environment and reflect it through the eyeball to the retinal implant. An adjustable light-processing feature is installed in the glasses that can be manipulated to improve the quality and resolution of vision. The retinal implant then converts the reflected light into electrical impulses, which the optic nerve transmits to the visual cortex — an area of the brain responsible for converting electrical impulses into vision.
Various physiological processes involved in generating vision are far more complex than presented here. However, this is the idea by which Professor Pallanker’s implant may improve vision in people with AMD.
The efficacy of this innovation
The current studies using animal models show promising results. Extrapolating these results to humans means blind people owing to AMD would have an acuity of 20/80 when using the implant. This means they would see from 20 feet (6.1 m) what a person with normal vision would see from 80 feet (24.38 m). This is not the 20/20 vision most of us hope for, but it certainly is a substantial improvement in the quest to restore sight in people with disabling eye disorders.
The state of the evidence
The evidence on retinal implants has mounted significantly over the past two decades, even though the majority of it is derived from animal studies. This is a limiting factor, as the long-term efficacy and safety of new retinal implants in humans remain unknown. To this end, Professor Pallanker’s research group is aiming to initiate a robust clinical trial looking at the efficacy and safety of the retinal implant in humans. Patient recruitment is likely to start as early as next year.
Where to get a retinal prosthesis
To date, only three implants have regulatory approval for commercialization. The Argus II implant developed by Second Sight Medical Products, Inc (Sylmar, CA, USA) received Food and Drug Administration (FDA) approval for clinical use in 2011. Later in 2016, the Alpha-IMS developed by Retina Implant AG (Reutlingen, Germany) and the IRIS II bionic vision system developed by Pixium Vision (Paris, France) received a CE Mark. This means these products can be sold and marketed in Europe.
However, preference is given to people with conditions driven by severe retinal degeneration (e.g., AMD). It is expected that the utility of these products will be extended to people with other visual disorders in the near future. An alternative to buying a retinal implant would be getting involved in a clinical trial as a research participant. Pixium Vision has developed a system called PRIMA, which is undergoing testing. Clinical trials for a retinal implant developed by Professor Pallanker are expected to commence in 2024.
The burden of blindness resulting from AMD has been on a steady rise, primarily due to non-modifiable predictors of AMD, such as aging, heredity, and genetics. In this instance, the phrase “prevention is better than cure” does not hold, as the only plausible option is treatment. For years patients with AMD were condemned to a life plagued by blindness, depression, a lack of participation in meaningful life activities, and a poor health-related quality of life. Nevertheless, there is a newly-found hope in cutting-edge retinal implants that have shown promising results for their ability to improve vision. Considering the rate at which technology is advancing, it is reasonable to expect that future retinal implants will restore sight to full capacity.
- Frontiers in Neuroscience. The Argus-II Retinal Prosthesis Implantation; From the Global to Local Successful Experience.
- Translational Vision Science & Technology. Retinal Implantation of Electronic Vision Prostheses to Treat Retinitis Pigmentosa: A Systematic Review.
- Nature Communications. Electronic photoreceptors enable prosthetic visual acuity matching the natural resolution in rats.
- The Lancet. Global prevalence of age-related macular degeneration and disease burden projection for 2020 and 2040: a systematic review and meta-analysis.