Caroline and Cole Carper have been through more than your typical siblings.
"I can't imagine it being any different than the two of them being together, and going through this together," said their mother, Ashley. "They've had canes together, they've had to learn Braille together, they've gone to school for the blind and visually impaired together."
Early in their lives, they were both diagnosed with a rare genetic retinal disease called Leber congenital amaurosis.
"The doctor really said, 'There's nothing,'" Ashley Carper said. "'There's no medical treatments at this time.'"
Both Caroline, 12 years old, and Cole, 10 years old, were expected eventually to go blind. But their parents found an experimental treatment, and, two years ago, the kids enrolled together in a clinical trial.