Age-related macular degeneration (AMD) causes progressive vision loss in many elderly people, and no treatment is available for the so-called atrophic form of the disease. A neurostimulation system called Prima, including a subretinal implant, could change all that. The results of a clinical trial involving Inserm, Sorbonne University and CNRS - via the Institut de la vision -, the Hôpital Fondation Adolphe de Rothschild and the Hôpital national des 15-20 show that it partially restored sight in over 80% of participants with AMD, who recovered their ability to read letters, numbers and words. The results are published in the New England journal of medicine.

Age-related macular degeneration (AMD) is the world's leading cause of blindness. It generally occurs after the age of 60. It is characterized by the destruction of the macula, the central part of the retina responsible for fine, detailed vision - the kind that enables us to read or recognize faces - while peripheral vision is preserved. There are two forms of AMD. Atrophic AMD is characterized by the progressive disappearance of the photoreceptor cells that capture light and transmit images to the brain, leading to the irreversible loss of central vision.

To date, there is no treatment for advanced atrophic AMD, but an international team involving the Institut de la vision (Inserm/CNRS/Sorbonne Université), the Fondation Adolphe de Rothschild, the Hôpital national des 15-20, Stanford University and Science Corporation, has developed a neurostimulation system designed to restore vision in these patients. The device has already been tested in animals, and an initial clinical study at the Rothschild Foundation Hospital and 15-20, involving five patients, validated its suitability for human use. This time, the team has published efficacy and safety results for a larger number of patients at several European sites.

This new clinical study included 38 patients with atrophic AMD, recruited from 17 centers in five European countries, including several French sites. The average age of the patients was 78.9 years, with severely impaired vision. Their vision was assessed using standardized charts, i.e. the lines of letters found in any ophthalmologist's office. To be included in the clinical trial, the result of this test had to be a logMAR score ≥ 1.2 for at least one of the two eyes, i.e. the virtual impossibility of reading the letters displayed.

Efficacy and safety

All participants received retinal implants, and their vision was assessed six and then twelve months after surgery. The primary efficacy endpoint set by the investigators was the proportion of participants with an improvement in visual acuity of 0.2 logMAR or more. A total of 32 people completed the study. Of these, 81% reached this threshold of improvement, reading at least 10 more letters in the vision chart after one year when wearing Prima than when wearing their natural vision, and with no change in peripheral vision. And 78% had a 0.3 logMAR improvement 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 designed to assess the adverse effects induced by this device and its implantation. A total of 26 serious events were observed in 19 participants, all of which had been anticipated in the risk analysis. Most were ocular hypertension, but there were also retinal detachments, holes in the macula and subretinal hemorrhages. The vast majority of cases occurred within the first two months, and 95% were rapidly resolved, either spontaneously or by medical intervention. Tolerance was considered good. Further follow-up is planned up to 36 months.

"The benefits far outweighed 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 Université), the Hôpital Fondation Adolphe de Rothschild; the Hôpital national des 15-20; Sorbonne Université, Paris; and the University of Pittsburgh School of Medicine, Pittsburgh, USA. "Until now, other types of subretinal implants had been developed, with far less benefit. This is the first time that a system has enabled patients who have lost their central vision to read words and even sentences again, while preserving their peripheral vision", he concludes.