"I heard, 'cut deeper, pull harder,'" she says.
She woke up in the middle of surgery to remove a damaged eye, and as Contributing Correspondent Dr. Mallika Marshall, of CBS-owned WBZ-TV reports, she could hear every word and feel and remember everything.
Like most surgical patients, Weihrer's anesthesia consisted of a cocktail of drugs: one to put her to sleep, a painkiller and a paralyzing agent. But when the paralytic is working, it's impossible to speak or move.
"You have no control," says Weihrer. "You can do nothing."
And therefore impossible to let the doctors know that the sleep agent isn't working.
She was, she says, absolutely afraid.
Now, Weihrer's case is at the extreme end of the spectrum, but she's not alone. In fact, recent statistics show that one to two out of every 1,000 surgical patients experience some level of awareness - that's about a hundred patients a day.
"The problem of awareness can't be denied," says anesthesiologist Dr. Carl Rosow.
During surgery, Rosow uses a brain monitor, which he attaches to the patient's forehead.
"It takes the brain wave, which is a pretty unfriendly piece of information and turns it into a number," says Rosow.
It's specifically designed to tell him whether a patient is asleep.
But the majority of anesthesiologists have not yet embraced this technology. Partially, Rosow says, because the size of the problem has just come to light.
"We've made the presumption that a person who was really awake, especially if they were suffering pain, would surely show us," says Rosow.
But Weihrer, who couldn't do that, still suffers the trauma. She barely sleeps and is afraid to lie down.
She's been sleeping in a chair for more than five years, unable to go near a bed.
So Weihrer spends most of her time now running an Internet support group for other victims, most of whom, she says, don't speak out for fear of being called crazy.