I was investigating PFAS. Then a doctor told me to put it in my eyes.

Looking at my laptop screen had started to hurt.

This January, I spent many hours glued to my computer while investigating Minnesota’s ban on PFAS chemicals. But between research and interviews and trips on frigid days to a product testing lab, I was growing more and more uncomfortable.

The lights in the newsroom ceiling made my eyes ache. It felt like something was stuck under my eyelid, though nothing was there. The whites of my eyes had turned pink.

In February, I went to an optometrist who specialized in dry eye disease. She prescribed an eyedrop that is relatively new to the United States called Miebo.

A few days later, I got a text from an online pharmacy indicating a bottle was being sent to my house. I searched the medication online and immediately noticed its chemical name: perfluorohexyloctane.

Perfluoro, I thought, as in “per- and polyfluoroalkyl substances”? As in PFAS?

Was I supposed to put forever chemicals in my eyes?

Miebo, the eyedrop I was prescribed to use four times a day, was a type of PFAS. Three chemists I spoke to later confirmed that.

Manufacturer Bausch and Lomb didn’t dispute that description of the drug either. But spokesman Chris Clark said that the compound was not like other PFAS chemicals that are linked to cancers and serious illnesses, calling the drug “inert and nonreactive.”

“It does not react with or bind to other substances and is practically immiscible in water,” Clark wrote, using a word that means the chemical cannot mix easily into water. “In addition, Miebo is not metabolized, leaving the body unchanged.”

I was desperate for relief. But I decided to call some experts before I opened the bottle.

Many medications contain carbon-fluorine bonds, some of the strongest bonds in chemistry. Any chemical with this bond is a PFAS under Minnesota state law, but FDA-approved medications are exempted from a state ban.

Thirty percent of pharmaceuticals historically have had fluorine attached to them, in part to keep them stable while they travel through the body, said Ryan Altman, a medicinal chemist at Purdue University.

But Miebo looked different from many other fluorinated medications, three chemists agreed.

Half of the chemical is a repeated chain of carbon-fluorine bonds. Bill Arnold, an environmental chemist at the University of Minnesota, said Miebo reminded him of PFAS firefighting foam.

These aqueous film-forming foams spread into a layer that smothers dangerous fuel fires. This made them the standard at airports and military installations for decades, before it was widely known that the foams release PFAS that are known to be toxic into the environment.

There is no evidence that Miebo is toxic. But the medicine appeared to work similarly, by creating a film on the surface of the eye, Altman said. This synthetic film was designed to mimic the natural oils that should coat the eye surface and stop tears underneath from evaporating.

This was exactly the problem my doctor had described to me after an exam — the oils on my eyes were breaking up too quickly, allowing my tears to dry.

“The science behind it is pretty clever,” Altman said.

My primary question was whether Miebo could, over time, accumulate inside my body. This characteristic, along with the resistance to breaking down, is what gives PFAS the nickname “forever chemicals.”

Clinical studies conducted before Miebo’s 2023 launch convinced the FDA that the medicine was safe and effective. Two trials, one that lasted eight weeks and another that lasted a year, showed patients reporting fewer dry eye symptoms, over time, than a placebo group.

One eight-week study examined how the chemical might move around the human body. It reported “low” levels found in blood, according to the FDA’s label for the drug. An earlier 2018 study in rabbits dosed with the eyedrops showed the chemical building up in tears and meibomian glands, which create natural oils on the eye.

An independent review of all the clinical trials and studies conducted by 2024 for Miebo’s only ingredient said the drug had a “strong safety profile.” The authors also noted, however, that more research was needed on its movement in the body “to make it a safer option for use.”

Will Pomerantz, a medicinal chemist at the University of Minnesota who works closely with Arnold, said he did not think the compound could cross the ocular-blood barrier, a protective layer around the eye.

Rather, the chemical is volatile, he said, and most of it would probably evaporate off the eye.

But Pomerantz questioned whether the chemical might transform after it left the body of the person using it. Pomerantz and Arnold have studied how fluorinated medications and pesticides break down in the environment and water treatment plants. Sometimes, they transform into several other PFAS.

Both intend to examine the ingredient in Miebo. They already have some at the lab, Arnold said, because he’d seen it on TV commercials.

“Whenever anyone in my group sees an advertisement for a medication, we immediately look up the structure,” he said.

Miebo has proven a success for Bausch and Lomb. The company markets the drug with a television spot that includes a riff on the Yello song “Oh Yeah” (known from “Ferris Bueller’s Day Off”).

CEO Brent Saunders said on an earnings call in February that the drug raised $172 million in revenue in 2024. Bausch and Lomb expects “to hit the one million prescriptions milestone in a few weeks,” Clark, the company spokesman, said in an email.

Dr. Mina Massaro, an ophthalmologist and director of the Penn Dry Eye and Ocular Surface Center, said she has prescribed Miebo to many of her patients. She’s heard mixed reviews. Some like it. Some think it’s no better than an over-the-counter lubricating drop. Some find the oily substance ruins makeup.

She estimated 5% of her patients know that Miebo is a form of PFAS. For those patients, she discusses using the drops only during their worst episodes of dry eye, or using something else.

“Patients should ask, ‘What are my other options?‘” she said.

Dr. Amanda Maltry, an ophthalmologist and the president of the Minnesota Academy of Eye Physicians and Surgeons, said the drop seemed to work for some dry eye patients. She said she hadn’t yet had a patient who recognized the drop as a PFAS.

Products with the same chemical as Miebo have been available over the counter in some European countries for years. But in the U.S., “The main barrier to actually getting it to patients is cost,” Maltry said. Without insurance, Miebo can cost as much as $800 a month, she said.

I’d been lucky that my insurance covered the cost, and by early April, three unopened bottles of Miebo were sitting in my medicine cabinet.

Warmer weather and more humid air had helped my dry eye symptoms. But the transition to spring, and the other strategies my doctor recommended, hadn’t totally solved the problem.

I didn’t have another appointment with my eye doctor until May. So I decided to finally try Miebo.

The colorless drop slipped out of the tiny bottle with almost no pressure, and landed on the inside rim of my lower right eyelid. It didn’t feel all that different from the lubricating drops I’d been using to little effect for months, but the sensation was a bit warmer.

My eyesight was blurry for a few minutes. And the dull, itchy pain I’d been dealing with all day had, for the moment, abated.

The drops seemed like they might help me, for at least the next few weeks. But knowingly dropping PFAS into my eyes still felt weird.

At my next eye doctor appointment, I decided to ask about other options.