In a clip shared on TikTok, the 'Roar' singer can be seen trying to correct the problem by bringing her hand to her temple, but it doesn't seem to work.
Eventually, the eye sorts itself out, but fans were left questioning what had happened following the incident, which has since sparked some bizarre conspiracy theories among social media users.
For reasons that aren't quite clear, anti-vaxxers have jumped to the conclusion that it was a side effect of a Covid-19 jab.
And another wrote: "Isn’t Katy Perry the one who sings that new hot song called 'Eye of the Pfizer?'"
It shouldn't need saying, but to be clear, there is zero evidence to suggest that
Covid vaccines cause any eye issues.
Other fans had more plausible theories about what caused the eye issue, suggesting it may have been a result of her make-up.
One person wrote: "Her lash glue wasn’t all the way dry."
A second said: "That be the glue on the eye lashes my eyes always do that don’t let me sneeze."
[caption id="attachment_364832" align="alignnone" width="1006"]
Some suggested the eye issue could have been a result of some make-up (TikTok/@katyperrytv)[/caption]
While a third, who said she'd spoken to a friend who was a professional make-up artist, said: "Katy has false lashes on in this. It's likely there's something in her eye, or bothering her eye, but she can't rub them because it will ruin her make up.
"Stage make up is very heavy and will get everywhere when you touch it. She's gentling pulling her temple area to try and alleviate the itch or clear whatever is bothering her eye without doing damage."
It could also simply be a case of a the singer having a lazy eye, and Perry has previously spoken about having what she calls her "wonk eye."
During last year's American Idol, Perry reassured 16-year-old Caleb Kennedy after he said he was self-conscious about his lazy eye.
“I have a wonk eye as well, and I used to be worried about it,” she said.
“Then a bunch of my fans created a fandom over my wonk-eye. I even have a fandom that calls itself, ‘Katy’s wonk-eye.’
"It's my right eye. So just celebrate all that stuff. Don't worry about it."
Speaking in 2011, Perry explained: "I got a prescription for my wonk eye to make [it] go bigger whenever I take pictures because I have a slight wonk."
