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Hundreds of thousands of Americans are battling hereditary vision loss. But stopping one of its root causes is a huge obstacle for researchers.

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Now University of Florida scientists say they can shut off the mutant gene that causes retinitis pigmentosa, one of the leading inherited causes of blindness. By injecting a corrective protein directly into the eyeball, researchers say they are able to cancel out the disease's faulty genetic code in lab animals, and perhaps one day in people. Using molecules carried into the eye by gene therapy, researchers successfully reduced production of the toxic form of rhodopsin, while leaving the healthy version unaffected. Rhodopsin is the gene essential for sight.

Dr. Marina Gorbatyuk / UF genetics expert

"We have reduced the amount of mutated rhodopsin and reduced the levels of mutated protein, and that allowed normal protein production to happen in the retina."

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The healthy version of the rhodopsin protein remained in the eye, available to boost the efforts of photoreceptor cells essential for vision. Merely reducing the amount of mutated protein may be enough to stabilize vision loss in people with retinitis pigmentosa. But scientists are now looking toward using gene therapy to deliver corrective genes to the eye in an effort to restore vision, first in lab animals, and perhaps eventually in human patients.

Dr. Marina Gorbatyuk (gore-bott-yuck)/ UF genetics expert

"It has been shown that gene therapy is a very useful instrument to cure eye diseases, and we hope that this therapy will also be able to be used to cure diseases caused by mutations in the rhodopsin gene as well as other genes."

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At the University of Florida Health Science Center, I'm Mike Garrison