Gene Therapy Cures Canines of Inherited Form of Day Blindness

PHILADELPHIA –- Veterinary ophthalmology researchers from the University of Pennsylvania have used gene therapy to restore retinal cone function and day vision in two canine models of congenital achromatopsia, also called rod monochromacy or total color blindness. Achromatopsia is a rare autosomal recessive disorder with an estimated prevalence in human beings of about 1 in 30,000 to 50,000. It primarily affects the function of the cone photoreceptors in the retina and serves as a representative model for other more common inherited retinal disorders affecting cones. Cone function is essential for color vision, central visual acuity and most daily visual activities, which underlines the importance of the newly developed treatment. The treatment cured younger canines regardless of the mutation that caused their achromatopsia. It was effective for the 33 months of the study and most likely is permanent; however, researchers also observed a reproducible reduction in the cone therapy success rate in dogs treated at 54 weeks of age or older. The successful therapy in dogs was documented by the restoration of the cone function using electroretinography and by objective measure of day vision behavior.