US actor Ashton Kutcher revealed for the first time that he had a health scare two years ago that affected his sight, hearing and equilibrium.

In a preview clip of Monday’s episode of television series Running Wild with Bear Grylls, the actor disclosed that he was diagnosed with a rare form of vasculitis- an autoimmune disease which causes inflammation of the blood vessels.

“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,” Kutcher told host Bear Grylls during the show, which takes celebrities on a 48-hour journey where they face inhospitable conditions.

“It took me like a year to build it all back up,” Kutcher added.

The 44-year-old father of two went on to express appreciation for his senses and his ability to walk, while noting that he is “lucky to be alive”.

“You don’t really appreciate it until it’s gone. 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’,” Kutcher disclosed.

During the episode, Kutcher also explained how this experience has shifted his outlook on life.

“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? You start surfing on top of your problems instead of living underneath them,” he said.