A retinal implant that partly restores sight in people with a common form of blindness . This is the first time that such a device 鈥� which enables people with a type of severe vision loss to read letters, numbers and words 鈥� has been approved anywhere in the world.
鈥淲e鈥檝e had patients who could recognise the face of the Queen and others who鈥檝e drawn the Sydney Opera House through the device,鈥� says at Science Corporation in Alameda, California, the company behind the implant.
Called the PRIMA implant, the device restores functional central vision 鈥� the straight-ahead sight required to see fine details and read words 鈥� in people with geographic atrophy. Affecting about , geographic atrophy is a progressive and irreversible form of dry age-related macular degeneration. This describes the slow deterioration of a part of the retina called the macula as retinal cells die off and are not renewed.
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Existing treatments for geographic atrophy are extremely limited. In the US, two medicines 鈥� given as shots in the eye 鈥� are approved that block proteins that may damage the retina. 鈥淭he PRIMA implant is an impressive achievement,鈥� says at Wills Eye Hospital in Philadelphia, Pennsylvania. 鈥淲e have two [US Food and Drug Administration]-approved medications for the treatment of geographic atrophy that slow down the progressive disease, but unfortunately, cannot bring back lost vision.鈥�
The implant 鈥� which is about the size of a pinhead and is inserted beneath the retina 鈥� is used alongside glasses with a frame-mounted camera. This captures and processes images, then projects the result onto the implant鈥檚 chips using near-infrared light. We can鈥檛 see in this wavelength, so the process doesn鈥檛 interfere with any existing vision.聽
These chips then convert the near-infrared light into electric pulses to stimulate neurons called bipolar cells, which are typically not damaged by macular degeneration, in the retina. Ordinarily, bipolar cells work with rod and cone cells, which convert light into electrical signals and are affected by macular degeneration. The PRIMA system bypasses rod and cone cells so bipolar cells can create electrical signals that can be interpreted by the brain.
The glasses generate electricity directly from light, similar to solar panels. 鈥淭his means patients don鈥檛 need a tethered power source,鈥� says Shahida.聽
In a small study published in October last year, PRIMA restored central vision and improved visual acuity in about 80 per cent of cases. 鈥淣ormal vision in the US is 20/20 and blindness is 20/200,鈥� says , also at Science. 鈥淧atients using PRIMA reached about 20/160, so they went from blind to not blind.鈥澛�
Most of the side effects were related to the surgery and resolved within two months. 鈥淭he physical recovery is quick, and some people feel better within a day,鈥� says Brodie. 鈥淎fter the implant, we train patients on using the glasses, [including] head positioning and pupil alignment.鈥�
Before the intervention is widely used, more research is needed on a larger group of people with long-term safety data, says Garg. The researchers also need to uncover if the implant only benefits people with certain patient- or condition-related characteristics, he says.
The intervention has received a CE certification mark under the European Union Medical Device Regulation, which enables it to be used in the European Union and the UK. PRIMA has also received Breakthrough Device and Humanitarian Use Device designations from the FDA, 鈥渨hich is an important pathway toward approval in the United States鈥�, says Shahida.聽
The first commercial use of PRIMA is expected soon in Germany and in the UK later this year, says Shahida. 鈥淲e鈥檝e already selected sites [in Germany], trained surgeons there and plan to begin our first surgical procedures soon,鈥� he says. 鈥淥ur goal is to commercialise this technology globally and help as many people as possible.鈥澛�
The team is also looking into the implant鈥檚 potential for other eye conditions, like Stargardt disease, which mainly affects the macula, says Brodie.
