From butter boards to viral dances, social media has spawned a host of fads, but experts have warned against the latest trend: eye-tattooing. The procedure, known as keratopigmentation, is a recent development and can be used for therapeutic purposes to improve the appearance of eyes. This can include for people who have been left with scars on the transparent front part of the eye, known as the cornea, as a result of infection, disease or injury, or who have aniridia, a condition where the iris has not formed properly. However, experts have raised concerns the procedure is becoming a popular aesthetic trend, with influencers posting TikTok videos of them undergoing surgery to permanently change their eye colour – often from brown to blue or green. Alex Day, a consultant eye surgeon and ophthalmologist at Moorfields private eye hospital in London, said the procedure was not available for purely cosmetic reasons in the UK, meaning those seeking eye tattoos tend to go abroad. But, he added, problems can emerge in the months that follow, with potential complications including blindness. “These are people that have healthy eyes, they have no problems with their eyes, and then they go and have a procedure purely for[cosmetic reasons] that could have huge long-term implications with regards to eye health and vision that will affect them for the rest of their lives,” he said. Keratopigmentation typically involves the patient being given a local anaesthetic before a surgeon makes a cut in their cornea using a laser or needle. This creates a tiny pocket into which pigments are injected. These pigments mask the natural colour of the iris that is normally visible through the transparent cornea, resulting in an apparent colour change. While Day said he had not himself yet seen patients who have undergone the procedure, changing eye colour is a growing trend on social media, leading to concerns among eye specialists that problems will follow. It is not the first time concerns have been raised over eye tattooing. In January, the American Academy of Ophthalmology issued warnings over keratopigmentation and another eye-colour-changing technique known as iris implant surgery, noting the procedures carry serious risks for vision loss and complications. For keratopigmentation, these include light sensitivity, damage to the cornea that could result in vision loss, infections, leakage of the dye into the eye and reactions to the dye resulting in inflammation. “Patients contemplating these procedures for cosmetic reasons alone must weigh these serious risks against the potential gain,” the organisation stated. Day said there have also been reports of colour touch-ups being needed, adding that people who wish to change the colour of their eyes are better off using coloured contact lenses. However, he said it was important these are prescribed and dispensed by a contact lens practitioner who has examined the individual, rather than being bought online. The warnings come as the first world congress devoted to the keratopigmentation is scheduled to take place this month in Spain. Jorge Alió, a professor and chairman of ophthalmology at Miguel Hernández University in Spain, who is president of the conference and who has developed the procedure, said the purpose of the event is to generate surgical protocols based on evidence about the therapeutic and cosmetic use of keratopigmentation. Alió added there was increasing demand for the surgery for cosmetic reasons, but while it was sometimes advertised as a procedure similar in character to the use of colour contact lenses, Alió warned that was not the case. “The procedure should be done only by adequately trained and medically well-educated corneal surgeons with the knowledge about patient selection criteria, complications and pigments to use,” he said, adding not all pigments were safe and stable when injected inside the cornea. However, Alió did not object to surgeons with appropriate expertise offering the technique to selected patients for cosmetic-only purposes. Indeed, Alió himself has carried out research in the area. “Every innovation is disruptive and controversial,” he said. However, Day said no surgery that aims to change the colour of healthy eyes has been shown to be safe. “No one should risk their vision by undergoing surgery to change their eye colour,” he said.