The Canadian star has had to cancel a number of shows - including the one for Saturday night in Niagara Falls - after suffering a detached retina. He's been admitted to hospital for surgery and many of his future performances are off until further notice. 

Mochrie, who was born in Scotland but is unapologetically Canadian, has been involved with a new "Whose Line"-type improv show involving a hypnotist and willing members of the audience. It's been a hit and is often sold out in the theatres where it plays. 

The show must go on - but not until Mochrie recovers. When that date comes remains to be seen. 

‘Whose Line Is It Anyway?’ Star Colin Mochrie Has Medical Emergency, Cancels Tour Dates