​Vision loss is a major cause of morbidity and a major fear for many people. The main causes of vision loss originate from the retina, the light-sensitive layer at the back of the eye. The central part of the retina, called the fovea, contains exclusively cone photoreceptors, which are specialized for high-acuity color vision. Diseases affecting the fovea are especially devastating, as patients lose their ability to read and recognize faces. Blindness is currently an untreatable medical condition and represents a significant unmet medical need.

Optogenetics is a form of gene therapy that uses light-sensitive proteins to control biological processes. This technique can be particularly useful for vision restoration, as remaining cells in the blind retina can be made light-sensitive through targeted expression of an optogenetic protein.

 

Cone-targeted optogenetics

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At the IOB, we have discovered that approximately two-thirds of patients who are blind due to inherited retinal degeneration and age-related macular degeneration retain non-functional ('dormant') cones in the fovea. This creates a therapeutic opportunity, as these dormant cones can potentially be reactivated by the targeted expression of a light-sensitive protein.

To target these dormant cone photoreceptors, we developed a cone-targeting optogenetic vector that can selectively express a light-sensitive protein in human cones and activate them. We used a human retina model to demonstrate that cone-targeted optogenetics restores retinal light sensitivity and retinal computations. The optogenetically treated retina responded to light stimulation just as normal human retinas do.

This therapy is currently being translated to the clinic and offers hope to patients who have already lost vision. We founded a spinout company, RhyGaze AG, which will further develop the therapy and launch clinical trials within a few years. The AAV vector will be subretinally injected to patients to reach foveal cones. Cone-targeted optogenetics has the potential to restore high-acuity vision in blind patients who retain cones in the fovea.

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