The condition, caused by inflamed blood vessels, left him temporarily unable to see or hear.
Ashton Kutcher revealed he suffered from a rare form of vasculitis two years ago that left him temporarily unable to see or hear.
The 44-year-old actor told Bear Grylls about his struggle with the disease while filming for Running Wild with Bear Grylls: The Challenge. The episode will air Monday evening at 9pm ET on National Geographic.
"I had this weird, super rare form of vasculitis, that like knocked out my vision, it knocked out my hearing, it knocked out like all my equilibrium," Kutcher told Grylls of the condition, which involves inflammation of the blood vessels. "It took me like a year to build it all back up."
"You don't really appreciate it until it's gone," he continued. "Until you go, 'I don't know if I'm ever going to be able to see again, I don't know if I'm ever going to be able to hear again, I don't know if I'm ever going to be able to walk again.'"
Grylls listened intently, telling Kutcher "What an ordeal. Talk about strength through adversity!"
Kutcher responded that he's "lucky to be alive," and that "the minute you start seeing your obstacles as things that are made for you, to give you what you need, then life starts to get fun, right?" he said. "You start surfing on top of your problems instead of living underneath them."
Like seasons before, Grylls will teach the celebrities a set of essential survival skills that they will later put to the test in some of the most intense outdoor settings.