Reality star Jack Osbourne has been diagnosed with multiple sclerosis (MS).

The 26-year-old, who has recently become a father, was found to have the incurable autoimmune disease after he lost 60 per cent of the vision in his right eye.

"While I was waiting for the final results, I got really, really angry," he said in an interview with Hello! magazine.

"Then I got really sad for about two days, and after that I realised, being angry and upset is not going to do anything at this point - if anything it's only going to make it worse.

"'Adapt and overcome' is my new motto."

He said he has spoken out to raise awareness of the condition.