A French ophthalmologist is performing surgery that can permanently change the color of your pupils. But not everybody agrees that it’s safe.

Called Femtosecond Laser-Assisted Annular Keratopigmentation, or FLAAK, its creator Francis Ferrari has invited plenty of controversy since inventing the procedure over a decade ago and opening his clinic in 2019. The American Academy of Ophthalmology has issued two warnings against the procedure, and it’s still not approved by the US Food and Drug Administration, according to a recent New York Times piece on the trending practice.

Sometimes called corneal tattooing, it involves coloring the cornea, the eye’s crucial protective barrier and outermost lens, which puts the rest of the organ at risk of suffering lasting damage, some experts argue.

“I think there’s a lot of fear among ophthalmologists, especially because there’s not really any long-term data on the procedure itself and the pigments that are used,” Amita Vadada, an ophthalmologist and a clinical spokesperson for the AAO, told the NYT. “The eye is a very sensitive organ, immunologically,” she added.

According to the NYT, the surgery goes like this: first, Ferrari numbs the patient’s eyeball. Then he uses the eponymous femtosecond laser to carve a tunnel in each cornea, which is then widened using a surgical hook. From there, he uses his trademark “Ferrari scalpel” — a tool he designed and patented — to shovel pigment into each of the waiting corneas, before painting them with careful brushstrokes. And voilà: your eyes are now “Riviera blue,” “honey gold,” or an uncanny shade of green.

From the way Ferrari describes it, your eye color is really determined by the iris, the ring shaped muscle that controls the size of your pupil. So his technique works by “hiding” the iris by coloring on top of it, almost like a contact lens.

Yet, this is still incredibly risky, Vadada argues.

“Unlike other parts of the body, even low-grade inflammation of the eye can lead to permanent scarring, light sensitivity and pain.” she told the NYT. Keratopigmentation is “potentially altering the function of the eye.”

But any physical damage that may be incurred pales in comparison to the mental anguish that Ferrari’s patients have to endure for living with their boring, decidedly not-paled-colored eyes. And besides, FLAAK is absolutely safe he says — as safe as LASIK.

“There’s real suffering,” he told the NYT. “Of course, it would be better to accept one’s natural eyes, but there are some patients who aren’t able to.”

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