Research suggests that gene therapy can effectively treat young children born color blind through pathways that connect the brain and retina.
Gene therapy was able to partially restore cone function in color-blind children, according to research conducted by the University of London, published in Brain. Achromatopsia affects rods and cones, both photoreceptors in the eyes. The disease, which results from gene variants, prevents cone cells from sending signals to the brain and causes color blindness, poor general vision and sensitivity to bright light.
“In our studies, we are testing whether delivering gene therapy at an early age can be most effective while the neural circuits are still developing. Our findings demonstrate unprecedented neural plasticity and offer hope that treatments could enable visual functions using signaling pathways. that have been dormant for years,” said co-lead author Michel Michaelides of the UCL Institute of Ophthalmology and Moorfields Eye Hospital, in a press release.
Researchers have explored ways to activate the cone cells and restore color vision. The 2 studies examine therapies that target a different gene and test their safety and efficacy in improving vision.
In the study, the researchers examined 4 people aged 10 to 15 years with achromatopsia. After receiving gene therapy in just 1 eye, researchers evaluated the efficacy of the treatment. Using a functional magnetic resonance imaging (fMRI) brain scan, the study authors identified changes in patients’ visual function after treatment by separating their cone signals from existing rod-driven signals after treatment.
After the brain scan, the team used a “silent substitution” technique to individually stimulate rods or cones to test the effects of the treatment. They compared the results of the study with data from 9 untreated patients and 28 patients with normal vision.
Prior to the test, no child had normal cone function on any test. After treatment, the results were comparable to those of patients with normal vision. Between 6 and 14 months after treatment, 2 of the 4 participants showed signs of cone-mediated signals in the visual cortex of the brain of the treated eye.
Those same 2 children also showed a difference in cone-assisted vision. After taking a psychophysical test, their results showed that the treated eye could see multiple levels of contrast.
“Our study is the first to directly confirm the widespread speculation that gene therapy offered to children and adolescents can successfully activate dormant cone photoreceptor pathways and evoke visual cues never before experienced by these patients,” said lead author Tessa Dekker of the study. UCL Institute of Ophthalmology, in a press release.
At the time of this study, researchers were conducting additional Phase 1 and 2 studies to test the neural pathways of the cones.
“We are still analyzing the results of our two clinical trials to see if this gene therapy can effectively improve the day-to-day vision of people with achromatopsia. We hope that with positive results and with further clinical trials, we can significantly improve people’s vision. with hereditary retinal disorders,” Michaelides said in the press release.
University College London. Gene therapy partially restores cone function in two completely colorblind children. Science Daily. August 24, 2022. Accessed September 2, 2022.