MONDAY, May 24, 2021 (HealthDay News) – Doctors have first used some form of gene therapy to restore partial vision in a blind person, it announced on Monday.
The team of researchers genetically engineered retinal ganglion cells to make them sensitive to light in a man whose eyesight was destroyed by retinitis pigmentosa, a genetic disorder that destroys cells that absorb light and convert it into brain signals.
With special protective goggles, the 58-year-old man from complete blindness was able to see a large notebook, a smaller staple, glass cups and even the stripes of a crossing, researchers reported in the June issue of the journal Nature Medizin.
“This is the first patient to report an improvement from optogenetics,” said lead researcher Dr. Jose-Alain Sahel, chairman of ophthalmology at the University of Pittsburgh.
Dr. Richard Rosen, director of retinal health care at Mount Sinai in New York City, described the news as “very, very exciting”.
continuation
“This potentially works for the full range of patients with these blind diseases,” said Rosen, who was not part of the study.
The structure of the human retina can best be described as inverted. Light-detecting photoreceptors are located at the very back of the retina, while ganglion cells in the front transmit visual information from photoreceptors to the brain via the optic nerve.
The field of optogenetics involves genetically altering cells so that they produce light-sensitive proteins called channelrhodopsins.
In this case, the researchers used optogenetics to make the top layer of ganglion cells sensitive to light and bypassing the non-functioning bottom layer of photoreceptors.
The researchers injected the man’s eye with a hollowed out cold virus that contains the genetic coding for a channelrhodopsin called ChrimsonR, which can sense amber light.
After giving his retina five months to accept the genetic change, they fitted him with special protective goggles that project visual images onto the retina using amber wavelengths of light.
The man had to practice with the glasses on, but after seven months of training he spontaneously reported signs of visual improvement, Sahel said.
continuation
“The brain has to learn a new language from the retina because what these ganglion cells tell the brain is not the normal activity of the ganglion cells,” said lead researcher Dr. Botond Roska, founding director of the Institute of Molecular and Clinical Ophthalmology Basel in Switzerland.
Electroencephalogram (EEG) readings, which measure electrical activity in the brain, showed that the man’s brain was actually responding to visual input from the eye.
“That’s why the retina is no longer blind,” said Roska.
The researchers warned that the man’s eyesight may not recover enough to read or recognize faces.
“You need a very high resolution to recognize a face. This is not yet possible with the approach we have used. Therefore, at this point we should not give anyone the hope that they can read or recognize faces because, for example, you have one need very high resolution, “said Roska.
But the amount of visions the man has achieved would be incredibly important to a blind person’s daily life, Rosen said.
continuation
“These are people who are completely blind. There is nothing. They see nothing,” said Rosen. “If they could see big obstacles in their path, it would be huge. Right now they’re tapping around with a stick to see what’s in their way. It’s a small step, but it’s a big step for these patients too . “
More people were injected with this gene therapy, according to researchers, but the COVID-19 pandemic affected their ability to travel to medical centers where they could exercise with the special glasses.
“Due to COVID, only this patient was treated in time to be able to test the goggles and exercise and to be taken back to the hospital and properly tested,” said Sahel.
The man hopes to get more training and ultimately use his restored vision as much as possible in his daily life, Sahel said.
While Rosen loved the report, he urged cautious optimism until more research was done on more patients.
“At this point, it’s a patient,” he said. “We don’t know how well this will work with others and it’s something that needs refining, but the proof of concept is really spectacular.”
continuation
More information
The US National Eye Institute is more concerned with retinitis pigmentosa, while Frontiers is more concerned with optogenetics.
SOURCES: Dr. Jose-Alain Sahel, chairman, ophthalmology, University of Pittsburgh; Richard Rosen, MD, chief, Retinal Services, Mount Sinai Health System, New York City; Botond Roska, MD, PhD, founding director, Institute for Molecular and Clinical Ophthalmology Basel, Switzerland; Nature Medicine, May 24, 2021
Comments are closed.