Corey was classified as legally blind due to an inherited disease called Leber's congenital amaurosis. Reading in school or riding a bike came with high degree of difficulty for him.
Corey's father, Ethan Haas, said it was "heartbreaking" to learn his son had the congenital disease.
However, when the Haas family learned about an experimental vision procedure from a doctor in Boston, Corey said he was "all for" anything that would help him see better.
The gene therapy trial at The Children's Hospital of Philadelphia changed everything for Corey and his family.