MADRID (EFE).— A new ocular prosthesis has managed to restore vision to people with irreversible blindness as a result of geographic atrophy, the last stage of a form of age-related macular degeneration (AMD), which affects approximately 5 million people in the world.
A team of European and American scientists had been working on the development of this device for two decades, which they successfully tested in a trial with 38 patients from 17 hospital centers in five countries. Their results were published in the “New England Journal of Medicine.”
The 32 patients, over 60 years old, suffered from the aforementioned geographic atrophy due to age-related macular degeneration, a hitherto incurable condition that slowly deteriorates vision. At the time of the trial they only had limited peripheral vision.
One year after using the device, called Prima, 27 of the 32 participants (84%) regained the ability to read letters, numbers and words through the eye that had lost sight.
Prima is a device made up of two parts: a wireless microchip that is implanted in the back of the eye and augmented reality glasses.
The microchip is ultra-thin, measuring two by two millimeters and shaped like a SIM card. It is placed in the eye through a procedure called vitrectomy, through which the vitreous gel is removed from the eye, located between the lens and the retina, and the chip is inserted under the center of the patient’s retina.
A small camera, installed in augmented reality lenses, captures images of the outside and projects them in real time, using infrared light, on the microchip installed in the eye.
The chip is sensitive to that infrared light projected from the glasses, and performs the functions of natural photoreceptors that have been damaged by the disease.
The device is photovoltaic and only needs light to generate electrical stimuli, so it does not need external power like other previous ocular prostheses, which required some type of “cable” coming out of the eye.
The design allows patients to use their natural peripheral vision along with central vision, through the ocular prosthesis, which helps them orient and navigate.
“The fact that a person sees simultaneously with prosthetic and peripheral vision is important because they can merge them and make the most of vision,” says one of the authors, Daniel Palanker, an ophthalmology researcher at the American University of Stanford, in a statement from the center.
Patients began using the augmented reality glasses four to five weeks after the microchip was implanted in the eye.
Although some were able to distinguish the patterns immediately, most’s visual acuity improved after months of training, similar to other implants developed to restore hearing.
Of the 32 patients who completed the one-year trial, 27 were able to read and 26 showed a clinically “very significant” improvement in visual acuity, which was defined as the ability to read at least two additional lines on a standard eye chart.
Participants in the clinical trial managed to achieve visual acuity of up to 20/42. This capacity improved, on average, in 5 lines, with some recovering it in 12 lines.
Most participants use the prosthesis in their daily lives to read books, food labels, or street or public transportation signs.
The lenses allow you to adjust contrast and brightness and have a zoom to magnify up to 12 times. According to the authors, two-thirds of the participants have expressed medium-high satisfaction with the device.
Nineteen of the 32 experienced side effects, including ocular hypertension, peripheral retinal tears, and blood pooling under the retina, but the contraindications resolved within a maximum of two months and did not put the patient’s life at risk, the authors report.
At the moment, Prima only offers vision in black and white, without intermediate tones, so researchers are developing software that will allow us to distinguish the entire range of gray tones.
“The first desire of the participants is to read, but the next is facial recognition, and for this we need software that recognizes gray tones,” says Palanker.
He and the rest of the team are also working on chips that offer higher resolution vision, and on more elegant-looking glasses. Another goal is to test the device for other types of blindness caused by loss of photoreceptors.
This successful human trial of the Prima device is the culmination of decades of development, prototyping and animal experiments.
DailyImprovement
The majority of participants in the trial use the prosthesis in their daily lives to read.
Benefits
The design allows patients to use their natural peripheral vision along with central vision through the ocular prosthesis, helping them orient and navigate. Most people’s visual acuity improved after months of training, according to the study.