Born with brown, blue, or hazel eyes, some patients are now turning to French ophthalmologist Francis Ferrari and spending at least €7,000 for a permanent cosmetic procedure to change their eye colours in less than an hour.

Mr Ferrari, 67, developed the Femtosecond Laser-Assisted Annular Keratopigmentation (FLAAK)—the procedure that changes eye colour—in 2013, alongside Spanish ophthalmologist Professor Jorge Alió.

Raised in Luxembourg, Mr Ferrari studied ophthalmology at the Eberhard Karls University of Tübingen in Germany. He has earned global recognition for cosmetic keratopigmentation and trained many surgeons since performing the first FLAAK procedure same year.

Mr Ferrari, who has practised ophthalmology since 1994, owns the New Eyes Paris clinic and performed over 2,000 operations on patients from five continents over the past decade, according to the facility’s website.

Prior to adopting the technique, he specialised in cataracts, vision correction, and general eye disorders.

He said he got the idea for keratopigmentation, originally designed to treat aniridia, in December 2011 after reading discussions by French ophthalmologists.

“I thought to myself that it would be good to find a technique that permits you to change the colour of your eyes in a safe way, and then I thought, the cornea,” Mr Ferrari told The New York Times.

When he could not find a medical device to distribute pigmentation around the cornea, he designed one.

Mr Ferrari, who said he had trained more than 15 surgeons in the technique, began experimenting with the FLAAK procedure on rabbits.

He said the procedure helps patients achieve their desired appearance and is safer than LASIK surgery, carries fewer risks than contact lenses, and safer than laser depigmentation and iris implant surgery, another eye-colour-changing technique.

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

However, the procedure has drawn criticism within the ophthalmology community due to concerns about potential complications, including infections, visual impairments, and blindness.

To achieve the colour change, keratopigmentation, also known as corneal tattooing, is performed using a femtosecond laser and takes between 30 and 45 minutes, according to Mr Ferrari. He said patients may experience glare and dry eyes, although these symptoms typically disappear after a few weeks.

While the result is permanent, Mr Ferrari said the pigment fades over time, and a touch-up may be considered. He added that the procedure can be partially reversed by removing about 80 per cent of the pigment, although the process is complicated and not advisable.

He said the procedure has, over time, helped people change natural eye colours to pigments ranging from pistachio and olive green to “Riviera blue,” “honey gold,” and “ocean.”

Mr Ferrari said the procedure does not change the colour of the iris. Instead, it colours the space in front of the cornea after a circular incision is made through which the pigment is injected.

“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,” said Amita Vadada, an ophthalmologist and a clinical spokesperson for the American Academy of Ophthalmology.

She added, “Unlike other parts of the body, even low-grade inflammation of the eye can lead to permanent scarring, light sensitivity, and pain,” she said, adding that with keratopigmentation, “you’re potentially altering the function of the eye.”