Gene therapy for glaucoma is currently showing some efficacy in animal experiments, but its efficacy has not yet been proven in humans. Glaucoma is the leading cause of visual impairment and blindness, caused by irreversible neurodegeneration of the optic nerve. Gene therapy can protect optic nerve cells by utilizing activation of the calcium/calmodulin-dependent protein kinase II (CaMKII) pathway to regulate retinal ganglion cells. The U.S. National Eye Institute found in mouse experiments that 77% of ganglion cells survived 12 months after intoxication in mice receiving gene therapy, compared to 8% in control mice, confirming the efficacy of gene therapy. Gene therapy is still in the testing phase in humans.