Optogenetics is an emerging new paradigm that is being used to uncover how neurons communicate and form such complex brain functions. This method involves the genetic integration of light-activated channels into cell membranes to converse light-based, optical control (both activation or deactivations) of physiological processes. The use of optogenetics has enabled the mutation-dependent, circuit-specific restoration of neuronal function in patients with neurological diseases like retinitis pigmentosa (RP), which is a neurodegenerative eye disease-causing complete blindness due to loss of photoreceptors. RP is a progressive and inhered group of genetic disorders, that causes vision loss due to mutation which causesa breakdown of light-sensitive photoreceptor cells in the retina. Scientists are now successful in partially recovering the function of neurons in the patient of retinitis pigmentosa using optogenetic therapy.
Optogenetic vision restoration in the patient of the late stage of RP after vision loss is one of its kind experimental gene therapy. It has given hope to those who have lost vision decades ago secondary to neurodegenerative eye disease. RP is affecting only 1 in 4,000 individuals but still has managed to affect almost 2 million people worldwide.
As a part of the PIONEER, clinical trial, a 58 years old man who was diagnosed with RP (an inherited group of disorder) was suffering from vision loss, is now able to partially see again with one eye, thanks to a combination of gene therapy and pulses of light stimulated (optogenetics) on his eye, courtesy of special goggles and Jose-Alain Sahel and team. This is an open-label phase 1/2a PIONEER study, registered at the clinical trial protocol (ClinicalTrials.gov identifier: NCT03326336) Though this is an approach of optogenetics for vision restoration is still in the experimental stages, but it has given hope to many.
The patient who was a part of this experiment had limited visual acuity to light perception, which means he could differentiate light from darkness but couldn’t make out anything else without assistance. But the same man can now see in one eye. This experiment is the first time that optogenetic vision restoration has been successful in delivering partial functional recovery to a neurodegenerative disorder like RP.
This first evidence was obtained by ophthalmologist José-Alain Sahel from the University of Pittsburgh who explained that they injected optogenetic sensor-expressing gene therapy, in combination with a light stimulating goggles to successfully recover the partial visual function in the patient have diagnosed RP and who had visual acuity of one light perception.
For the study, the man was injected with intravitreal injection in the eye, most affected by RP to deliver an adeno-associated virus. This method is a type of gene therapy in which the viral vector can infect the human tissues with a useful payload. The virus then directed the production of light-sensitive proteins that were capable of boosting the function of light perception in the damaged retina cells of that man. To let the man partially see the objects, the researchers used special goggles that can burst the light corresponding to the shape and orientation of the objects in front. These light-stimulating goggles can capture images from the visual world with the help of a neuromorphic camera that is sensitive to changes in intensity, pixel by pixel as distinct events. This allowed the previously blind patient to successfully perceive, locate and touch objects (e.g.; notebook, staple, box, and tumbler) in front of him. This research has proven beneficial for the patient of RP.
Optogenetic vision restoration, neurodegenerative disease, visual acuity, retinitis pigmentosa, blindness, light perception, visual loss.