Ashton Kutcher 'Lucky To Be Alive' After 'Super Rare' Autoimmune Disorder Diagnosis

Ashton Kutcher is speaking up for the first time about a "super rare" autoimmune disorder that left him unable to see, hear, or walk a few years ago. Kutcher spoke about the disorder and the struggles he had to overcome on an upcoming episode of National Geographic's "Running Wild with Bear Grylls: The Challenge."

"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," he told Grylls. He also told Grylls that it took about a year to be able to build each up again.  "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.' Lucky to be alive," Kutcher said.

Vasculitis is a rare autoimmune disorder with different variations. The disorder can cause inflammation of the blood vessels which restricts blood flow and can lead to organ and tissue damage. According to the Mayo Clinic, symptoms of the disorder can include weakness in the hands and feet, abrupt hearing loss, and temporary blindness in one or both eyes. Most forms of vasculitis are rare and can be either short or long term.

The terrifying ordeal didn't hold Kutcher, 44, down for long. He views challenges in life as opportunities for growth, and this was no different for the actor who is now fully recovered. "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," Kutcher said. Grylls agreed and responded, "What do they say in survival? Storms make you stronger. And I think he's living proof of that."

This isn't the first health issue the "No Strings Attached" actor has dealt with in the public eye. Last year, Kutcher's wife, Mila Kunis, talked about how her husband gave himself pancreatitis from drinking "too much carrot juice" when preparing to play Steve Jobs in the 2013 movie "Jobs." Jobs was on a strict diet while dealing with neuroendocrine cancer, and Kutcher followed a strict fruit only diet to help him get into character. Kunis told host Sean Evans on an episode of the web series "Hot Ones" that her husband's diet put him in the hospital twice.

The couple, who have two children together, met on the set of "That '70s Show." They both recently filmed a scene in the reboot, "That '90s Show."

Kutcher's episode of "Running Wild with Bear Grylls: The Challenge" airs at 9 pm ET Monday night on National Geographic. This season of the show will be a little different than last. Grylls guests will be pushed to their physical and mental limits as before, but they will also have to prove they can survive when the pressure hits. Grylls will teach each guest a key skill that they will have to master and utilize in a high intensity moment to get out of the wilderness.