The new episode of Animal Planet’s Monsters Inside Me tells the terrifying, true story of Melanie, an Iowa college student whose opthamologist discovered she had a rare parasite eating her eye after she complained of light sensitivity and pain.
“What makes the Acanthamoeba paraside so dangerous is their ability to burrow deep into the tissue of the eyeball,” biologist Dan Riskin says in a clip exclusive to PEOPLE. “Once there, they can be hard to remove or even treat, which allows the parasites to feed on the host’s cells unchecked.”
Melanie returned to school a regimen of squirting a solution that her doctor likened to professional pool cleaner into her eye every hour for four days.
“When I put the eye drops in, the pain it caused was just intense burning,” she says. “It was an uphill battle, knowing at the top of the next hour you were going to have to do it again and having to set my alarm clock and get up all hours of the night. Just a continuous cycle of pain.”
Then, things took a turn for the worse: She woke up one morning to discover her entire eyeball was white and difficult to see with.
“It made me look possessed, and I was starting to lose my eyesight,” she says. “The parasite was completely taking over.”
To find out how Melanie fought the parasite, tune in to Monsters Inside Me on Thursday at 10 p.m. ET on Animal Planet.