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 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.