Hollywood actor Ashton Kutcher has revealed his secret battle with a “super rare” disease that left him unable to see or hear for an extended period.

Kutcher revealed he was “lucky to be alive” after he was diagnosed with a rare form of vasculitis nearly two years ago.

He told National Geographic’s Running Wild With Bear Grylls: The Challenge that it took him almost a year to fully recover from the disease.

“Two years ago I had a weird, super-rare form of vasculitis that knocked out my vision, knocked out my hearing and knocked out all my equilibrium,” Kutcher said.

Vasculitis is an autoimmune disease that results in the inflammation of the blood vessels and restricted blood flow. There are many types of the disease – Kutcher did not disclose the specifics of his diagnosis.

“It took me like a year to build it all back up again,” the That ’70s Show star said.

“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, who has since fully recovered, added that he was lucky to be alive”, telling of his personal growth since his health scare.

“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,” he said.

“You start surfing on top of your problems instead of living underneath them.”