Gene therapies for degenerative eye conditions are becoming a reality, with several treatments already in clinical trials and others in development. These therapies aim to correct defective genes, regenerate photoreceptors or ganglion cells, and restore lost vision. One such therapy, from French company SparingVision, aims to preserve remaining vision in patients with retinitis pigmentosa (RP), a genetic disorder that leads to progressive vision loss.

The treatment, called SPVN06, works by protecting the cone cells in the retina that are responsible for color perception and acute vision. These cells can become functionally dormant or die due to the toxic environment created by dying rod cells or from exposure to excess light. SPVN06 introduces a protein called rod-derived cone viability factor (RdCVF) into the retina, which promotes the survival of cone cells by increasing their glucose uptake. While SPVN06 is not a cure for RP, as the disease-causing mutation remains, it has the potential to slow disease progression and preserve remaining vision.

This is an important step forward, as there are currently no treatments available for the majority of patients with inherited retinal disorders. While gene replacement therapies have shown promise in treating specific inherited retinal disorders, it is neither economically nor technically feasible to develop over 200 different therapies to address every single condition. Generalized approaches, such as SPVN06, offer a potential solution for the many patients who currently have no treatment options.

SparingVision’s therapy is just one example of the progress being made in the field of ophthalmic gene therapies. Other treatments in development include therapies for age-related macular degeneration, glaucoma, and various types of retinal dystrophy. Fish, reptile, and bird species are able to regenerate retinal tissue in response to injury, but in mammals, the retina is unable to do so. This inability to regenerate leads to an inexorable loss of retinal cells and progressive vision loss in certain genetic diseases of the eye.

There are over 20 inherited retinal disorders, including RP, Leber’s congenital amaurosis, achromatopsia, Batten disease, Stargardt’s disease, and several types of retinal dystrophy. Over 260 different genes have been identified as being subject to causative mutations. However, only one gene replacement therapy has received regulatory approval, Spark Therapeutics’ Luxturna, which is indicated for patients with retinal dystrophy caused by RPE65 mutations.

While it will likely be several years before these therapies become widely available, the promise of being able to treat and potentially cure degenerative eye conditions is an exciting development for both patients and doctors. The ability to edit, regenerate, and reprogram eye tissue holds great promise for restoring lost vision and improving the quality of life for those suffering from these conditions.