How a blind patient mainly recovered his sight thanks to quality treatment
This is the first time that this technique, called optogenetics, has made it possible to obtain partial recovery of visual function, say the researchers behind this clinical trial, which involved French, Swiss and American teams.
The patient in the study has retinopathy pigmentosa, a degenerative genetic disease of the eye that destroys photoreceptor cells in the retina, leading to progressive loss of vision that usually progresses to blindness
Seven months later the patient began to report signs of visual improvement
the Institute of Vision
While he could just see the presence of light, the treatment presently permits him to find and contact objects, as indicated by the examination, distributed Monday in the diary Nature Medicine.
In ordinary vision, photoreceptors in the retina use proteins fit for responding to light energy, opsins, which convey visual data to the cerebrum by means of the optic nerve.
To reestablish affectability to light, the patient was infused with the quality encoding one of these proteins, called ChrimsonR, which identifies golden light, the examination portrays.
Large notebook, small box
Almost five months after receiving the injection, to give his body time to produce this protein in sufficient quantity, he performed various exercises, equipped with dedicated glasses fitted with a camera.
Designed for the occasion by the researchers, these glasses make it possible to project amber-colored images on the patient's retina.
"Seven months later, the patient began to report signs of visual improvement", explain in a press release the Institute of Vision (Sorbonne University / Inserm / CNRS) and the Parisian hospital of Quinze-Vingts, specializing in ophthalmology. "With the help of the glasses, he can now locate, count and touch objects."
In a first test consisting of perceiving, locating and touching a large notebook and a small box of staples, he managed to touch the notebook in 92% of the cases but could only grasp the box in 36% of the tests.
A second exercise consisting of counting cups on a table was successful almost two out of three times (63%).
For the third test, a cup was alternately placed or removed from the table and the patient had to press a button indicating whether he was present or absent, while his brain activity was measured using a helmet of electrodes. electroencephalography.
A software interpreting the recordings of the electrodes was able to say with an accuracy of 78% whether the cup was present or not, confirming "that the brain activity is indeed related to the presence of an object, and therefore that the retina is not. more blind, ”says Prof. Botond Roska, one of the researchers who led the study.
One in 3,500
“If optogenetics, a technique that has already existed for twenty years, has revolutionized fundamental research in neuroscience (...), this is the first time internationally that this innovative approach has been used in humans and that its clinical benefits have been demonstrated ”, underline the two French organizations, which conducted the clinical trial in association with the University of Pittsburgh (United States), the Institute of Molecular and Clinical Ophthalmology of Basel (Switzerland), the Streetlab company and the French biotech GenSight Biologics.
Retinopathy or retinitis pigmentosa affects one in 3,500 people, according to the European Orphanet database, and can begin at any age, with a greater frequency of occurrence between 10 and 30 years.
The genes responsible are very numerous, but certain mutations are frequently found in people with the disease.
"Blind people with different types of neurodegenerative diseases of photoreceptors" but retaining "a functional optic nerve" will be "potentially eligible for treatment, explains Professor José-Alain Sahel, founder in 2009 of the Institute of vision, dedicated at retinal diseases. "But it will take time before this therapy can be offered".
Gensight Biologics, specialized in gene therapies for the treatment of neurodegenerative diseases of the retina, "intends to launch a phase 3 trial soon to confirm the effectiveness of this therapeutic approach", he adds.
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