Blindness
Optogenetic Restoration
The eye is a complex organ that allows us to perceive and communicate with our environment. To process information such as brightness, contrast, color, or movement, light enters the eye through the clear cornea and lens, and is captured in the retina. There, it is processed and ultimately transmitted to the brain via the optic nerve. If this path of information processing is disturbed or even interrupted, it leads to limitations or loss of vision. One of the main causes of such vision loss is degenerative retinal diseases, which are currently only partially treatable but not curable. Today, wet age-related macular degeneration (AMD) can be stopped by regular medication injections into the vitreous cavity, but often a limitation in reading ability remains. The dry late-stage form of AMD progresses more slowly, but when it extends under the visual center (= fovea), it leads to severe visual impairment, and currently only therapies that slightly slow down the progression are available. The results were not sufficient for approval in the EU. Retinal dystrophies also lead to progressive loss of vision. A subtype of these hereditary retinal diseases is retinitis pigmentosa, which begins in the outer parts of the retina and leads to a tubular restriction of the peripheral visual field, potentially causing complete loss of vision in the late stage. The described retinal diseases cause progressive death of the sensory cells (photoreceptors) of the eye. Ideally, the cells connected behind in the stimulus transmission survive longer and offer an opportunity for a novel therapeutic approach at this point.
Both electrical retinal prostheses and optogenetic approaches aim to activate surviving cells in the inner retinal layers when the outer retina degenerates, in order to restore vision in blind patients. To implement these treatment approaches, cameras integrated into glasses are required to convert the visual scene into a stimulation pattern.
With electrical retinal implants, the resolution of the perceived image is limited by the spread of neural activation from each electrode and the electrode spacing. These commercial devices can only restore coarse visual perceptions and can only reach a small portion of the retina.
In optogenetic approaches, on the other hand, nerve cells in the retina are converted into light detectors through the expression of opsins. This allows these inherently non-light-sensitive cells to be activated even when the upstream photoreceptors are no longer functioning. Building on our expertise, novel sensitive opsins are to be developed with the aim of achieving improved restoration of vision.
