The Liberty X singer was one of the celebrity recruits for the reality series currently airing on Channel 4 which sees contestants put through a version of Special Forces training in the Vietnamese jungle.
But the gruelling challenges are not the only nightmare for the recruits, as Heaton has told how she contracted "swamp eye" from the jungle's dirty water and said that parasites "found their new home" in her eye for months.
Celebrity SAS actually filmed its current series in September and October 2022, but even a year on, Heaton, 44, is struggling with the eye condition.
Posting a photo of her sore-looking right eye on Instagram ahead of Sunday's episode, where she was eliminated from the cast, Heaton asked people to "be kind" about her "wonky eye".
She wrote: "This is called “swamp eye”. A year ago after returning from #saswhodareswins parasite’s found in extreme dirty water from the jungle, decided to return in my eye with me.
"They lived in there & found their new home for over 3 months. Unable to see properly. To this day my vision is still slightly blurred in my right eye."
Heaton, who took part in Dancing On Ice in January, also told how swamp eye had caused her problems ahead of her next reality TV appearance.
She wrote: "I remember going straight into #dancingonice training with a patch on - almost until the live shows.
"People often comment on why I have a “wonky eye” - now you know ! #bekind"
Her celebrity pals offered their support, as Luisa Zissman commented: "Gosh you poor thing!! That show has so many lasting injuries that come with it great to watch tho!"
Meg Mathews wrote: "Oh babes ouch."
But Celebrity SAS directing staff Chris Oliver simply commented: "Terminator."
She said: "I remember Matt texting me about a week after I posted that (a photo of her swollen eye) on the group chat saying, 'I've got it too, what are you doing, where are you going?' I sent him where I had been (for treatment)."
She added of the condition: "To this day, I'm still quite blurry over my right eye and I haven't got the same vision."
Celebrity SAS: Who Dares Wins continues on Channel 4 on Sunday.
Watch a promo for Celebrity SAS: Who Dares Wins