Age-related macular degeneration (AMD) causes progressive vision loss in a large number of elderly people, and no treatment is available for the so-called atrophic form of this disease. A neurostimulation system called Prima, including a subretinal implant, could be a game-changer.
The results of a clinical trial involving Inserm, Sorbonne University and CNRS - via the Institut de la Vision -, the Adolphe de Rothschild Foundation Hospital and the National Hospital of the 15-20 show that it partially restored sight in more than 80% of participants with AMD, who were able to read letters, numbers and words again. The results are published in the journal
New England journal of medicine.
Age-related macular degeneration (AMD) is the leading cause of blindness worldwide. This disease usually occurs after the age of 60. It is characterized by the destruction of the macula, the central part of the retina responsible for fine and detailed vision; the part that enables reading or recognizing faces, while peripheral vision is preserved. There are two forms of AMD. The so-called atrophic form is characterized by the progressive disappearance of the photoreceptor cells that capture light and transmit images to the brain, causing irreversible loss of central vision.
To date, there is no treatment for the atrophic form of AMD at an advanced stage, but an international team combining the Institut de la Vision (Inserm/CNRS/Sorbonne University), the Adolphe de Rothschild Foundation, the National Hospital of the 15-20, Stanford University, and Science Corporation, has developed a neurostimulation system intended to restore vision in these individuals. This device has already been tested in animals, and a first clinical study conducted at the Rothschild Foundation Hospital and the 15-20, involving five patients, had validated the possibility of using it in humans. This time, the team is publishing results on efficacy and safety from a larger cohort and across several European sites.
This new clinical study included 38 patients with the atrophic form of AMD, recruited from 17 centers in five European countries, including several French sites. Their average age was 78.9 years and they had severely impaired vision. Their vision was assessed using standardized charts, namely the lines of letters found in any ophthalmologist's office. To be included in the clinical trial, the result on this test had to be a logMAR score ≥ 1.2 for at least one eye, meaning the near impossibility of reading the displayed letters.
All these participants received the retinal implant, and their vision was assessed six and then twelve months after the surgery. The primary efficacy criterion set by the investigators was the proportion of participants showing an improvement in visual acuity of 0.2 logMAR or more. In total, 32 people completed the study. Among them, 81% reached this improvement threshold, reading at least 10 additional letters on the vision chart after one year when wearing the Prima glasses compared to their natural vision, and without any change in peripheral vision. And 78% had an improvement of 0.3 logMAR and read at least 15 more letters with the glasses. The maximum benefit was a gain of 1.18 logMAR; the patient was able to read 59 more letters. At one year, 84.4% of participants reported being able to read letters, numbers, and words at home.
This trial was also intended to evaluate the adverse effects induced by this device and its implantation. In total, 26 serious events were observed in 19 participants, but they had all been anticipated in the risk analysis. These were most often ocular hypertension, but also retinal detachments, macular holes, or subretinal hemorrhages. The vast majority of cases occurred during the first two months and 95% were resolved quickly, either spontaneously or through medical intervention. Tolerance was considered good. Additional follow-up is planned for up to 36 months.
"The benefit proved to be much greater than the adverse effects," concludes José-Alain Sahel, senior author of this article and an international researcher affiliated with Inserm, the Institut de la Vision (CNRS/Inserm/Sorbonne University), the Adolphe de Rothschild Foundation Hospital; the National Hospital of the 15-20; Sorbonne University, Paris; and the University of Pittsburgh School of Medicine, Pittsburgh, USA.
"Until now, other types of subretinal implants had been developed, providing much less benefit. This is the first time a system has enabled patients who have lost central vision to start reading words, even sentences, again, while preserving their peripheral vision," he concludes.