Ashton Kutcher's recent revelation about his vasculitis diagnosis is bringing to light to an autoimmune disorder that can cause serious damage to the body.

"Like two years ago, 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," the That '70s Show alum shared in a preview of his appearance on an upcoming episode of Running Wild with Bear Grylls. "It took me like a year to build it all back up."