The sight of a blind Frenchman partially restored thanks to pioneering gene therapy
A Frenchman who suffered for a long time from a blinding degenerative disease saw his sight partially restored in one eye after a revolutionary treatment combining gene therapy and light stimulation from specially designed glasses.
The 60-year-old man was diagnosed with retinitis pigmentosa at the age of 25. His eyesight gradually deteriorated and he was declared disabled at the age of 44 in 2004.
Retinitis pigmentosa is an inherited genetic eye disease that causes vision loss due to the destruction of photoreceptor cells in the retina. It affects around 2 million people worldwide and around 30,000 in France, according to figures from the national research institute Inserm.
This is the first time this technique, called optogenetics, has allowed a human patient to achieve partial vision recovery, the researchers behind the clinical trial said.
An article describing the therapy was published in the peer-reviewed medical journal Nature Medicine on May 24.
It was headed by the French ophthalmologist Dr José-Alain Sahel and the director of the Basel Institute of Molecular and Clinical Ophthalmology, Botond Roska, as well as researchers from the Institut de la Vision in Paris and the University of Pittsburgh in the United States.
The patient was previously only able to perceive light patterns, but after therapy he is now able to locate and touch various objects.
In normal vision, photoreceptors in the retina use light-sensitive proteins called opsins, which deliver visual information to the brain via the optic nerve.
To restore his sensitivity to light, the patient was injected with the gene encoding one of these proteins, called ChrimsonR, which detects amber light, the study describes.
“This is obviously not the end of the road, but it is an important step,” Dr Sahel told The New York Times.
Seven months after receiving the injection, the patient’s vision began to improve, according to the study.
“With the help of the glasses, he can now locate, count and touch objects.”
The specially designed glasses project amber-colored images onto the patient’s retina.
During a test, the patient was able to locate and touch a large notebook in front of him 92% of the time. When a small box of staples was placed in front of him, he was able to find them 36% of the time.
In a second exercise, which consisted of counting the cups placed in front of him, the patient was successful 63% of the time.
Blind people suffering from various types of photoreceptor neurodegenerative diseases but who retain “a functioning optic nerve” will be “potentially eligible for treatment,” said Dr Sahel.
“But it will be some time before this therapy can be offered.”
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