NEW YORK (Reuters Health) – A wireless photovoltaic device implanted subretinally can restore central visual sensitivity in patients with geographic atrophy, an advanced form of age-related macular degeneration (AMD), according to a first-in-human clinical trial.
“None of the other implants so far achieved shaped vision, as we did,” Dr. Daniel Palanker from Stanford University in California told Reuters Health by email. “In addition, our resolution is much better and most importantly, results are consistent – every patient with an implant placed centrally and subretinally achieved acuity within 10%-30% of the maximum defined by the current pixel size (20/420).”
Electronic retinal prostheses aim to reintroduce visual information into the degenerated retina by electrical stimulation of the remaining neurons. Existing systems provide low visual acuity and employ trans-scleral cables.
Dr. Palanker and colleagues developed a wireless prosthesis in which photovoltaic pixels directly convert projected light patterns into local electric current and tested its safety and functionality in five patients with AMD.
After the implant surgery, residual natural visual acuity in the treated eye did not decrease in any patient during follow-up and, in fact, improved slightly in four of the five patients.
At 6 and 12 months, all five patients reported light perception in the atrophic zone elicited by the implant when the system was turned on and no perception when the system was turned off, according to the online report in Ophthalmology.
The three patients with optimal central placement of the implant demonstrated visual acuity ranging from 20/460 to 20/550 within 12 months, which is 10% to 30% below the theoretical resolution limit for the pixel size of this implant.
One of the two patients whose implant shifted slightly had visual acuity with the prosthesis of 20/800, while the other patient could not resolve letters or optotypes of any size.
All the procedures required to implant this device can be performed within 2 hours, as opposed to the 4 to 8 hours required with the two wired devices (Argus II and Alpha IMS).
“Prosthetic vision for AMD patients is possible,” Dr. Palanker said. “Now we should reduce the pixel size in order to improve resolution to better than 20/100.”
He added that a “new study with augmented reality glasses is underway, and it demonstrates simultaneous perception of natural and prosthetic vision.”
Dr. Samuel N. Markowitz from University Health Network, University of Toronto, who participated in studies of the Argus II retinal prosthesis, told Reuters Health by email, “Efforts are continuing worldwide to develop artificial vision, which is good news.”
“This is a preliminary study which could pave the way for future studies in this field, which is also a positive point,” he said.
Pixium Vision funded the study and had various relationships with the five authors of this report. Dr. Palanker holds patents owned by Stanford University which are licensed to Pixium Vision.
SOURCE: https://bit.ly/2TK2zrL Ophthalmology, online February 25, 2020.