PHILADELPHIA (CBS) — On Tuesday the FDA approved a groundbreaking gene therapy treatment developed by doctors at the University of Pennsylvania. That same treatment has helped changed the life of a star singer suffering from childhood blindness.

America’s Got Talent semi-finalist Christian Guardino developed a love for music at a young boy because a congenital eye condition took his vision.

“Growing up, I’d have to sit inside with my parents, with the lights on, because I couldn’t see enough to play with the other kids,” he said. “And I thought that was normal.”

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Elizabeth and Christian Guardino (Photo Provided by Elizabeth Guardino)

But one day Christian’s parents decided to take a chance and enroll him in a clinical trial at Children’s Hospital of Philadelphia with hopes to restore their son’s sight.

That’s when the Guardino family met Dr. Jean Bennett and her team who were given a rare opportunity to conduct clinical trials on children.

“We wanted to make sure that this had the highest level of safety and highest level of improvement in vision as possible,” Bennett said.

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Elizabeth and Christian Guardino along with Dr. Jean Bennett (Photo Provided by Elizabeth Guardino)

FDA approval has been a 20-year journey for Dr. Bennett and her husband Dr. Albert Maguire who developed the treatment for the gene mutation that affected Christian and many others.

Bennett says Guardino’s condition is “an inherited early onset blindness caused by defects in a specific gene called RPE-65. The treatment would only work for that particular form of blindness.”

Elizabeth Guardino, Christian’s mother, says they were scared at first but ultimately felt that the risk was well worth the potential reward.

“As time went by, I got to see more and more things like the moon and the stars,” Christian said. “I saw, in detail for the first time, my mother and father’s faces. It’s just been incredible.”

Elizabeth says she is eternally grateful to the doctors who changed her son’s life.

“They’re extraordinary, extraordinary human beings,” she said. “They really are.”

“Hopefully, it’s going to lead to other groundbreaking treatments for other diseases,” Elizabeth added.

Now that the treatment has been approved it will soon be available for anyone who can afford it, but experts say it could cost as much as $1 million.