In a historic move, the FDA approved a gene therapy this week that could save a person's sight.

The FDA says Luxturna worked in 93 percent of patients during clinical trials.

"America's Got Talent" star Christian Guardino was one of those success stories. He suffered from Leber congenital amaurosis, or LCA. Doctors told his mother, Beth, that Christian would eventually be completely blind.

Christian's parents decided to take a chance and enroll him in a clinical trial at Children's Hospital of Philadelphia with hopes of restoring their son's sight when he was 13 years old. 

Christian and other patients in the study had a defective gene called RPE65, which is responsible for producing a protein that makes light receptors work in the eye.

The gene therapy Luxturna was injected into the eye, which uses a benign virus to deliver healthy copies of the gene to the retina.

Christian says the gene therapy enabled him to see clearly for the first time in his life.

"I was able to see so many new incredible things. I was able to see the moon, I was able to see the stars … snow falling was a big one … and fireworks," says Guardino. "These are all things I was never able to see before, so looking at those things today are still incredible to me."

Luxturna is expected to be available at select treatment centers early next year. Spark Therapeutics, which makes Luxturna, said it will not announce the price until January.