But with Ana, Mosso is not sure if the headset will be enough. He hopes the virtual reality will help her avoid extra medication – but if she becomes anxious during the surgery, her already-high vital signs might spike. He has prepared an intravenous line just in case, ready to administer emergency medication if required.

But it isn’t. The surgeon pulls a large, pearly glob of tissue from Ana’s thigh, his fingers easing under her skin as he carefully snips it free. Then he mops the blood and stitches the wound. The procedure has taken just 20 minutes, and there are smiles all round as Ana thanks the team. Engrossed in the virtual reality, she barely noticed the scalpel slicing her flesh. “I was transported,” she says. “Normally I’m very stressed, but now I feel so, so relaxed.”

The monitors back up her story. Throughout the surgery, her blood pressure actually fell.

The amazing Spider-Man

In 2004, Mosso bought a Spider-Man game for his eldest son, and his life and career path changed. The game involved images projected onto a head-mounted display – an early form of VR. Mosso was struck by how immersed his son became in the game. “His Mom called him to go to dinner and he didn’t hear her, nothing,” he says. “I thought, what if I use this on a patient?”

Mosso began using the game during upper gastrointestinal endoscopies, in which a flexible tube with a camera on the end is fed through a patient’s throat into their stomach. The experience can be unpleasant and distressing. Patients often require sedation but Mosso encouraged them to play the Spider-Man game instead.

He asked the patients to score their pain and anxiety during the procedure and in 2006 presented his results at the Medicine Meets Virtual Reality conference in California. The idea of using VR to reduce the distress of medical procedures was pioneered at the University of Seattle, Washington, where cognitive psychologist Hunter Hoffman and colleagues have developed a VR game called SnowWorld, to help patients endure wound care for severe burns. Hoffman’s team have shown in trials that SnowWorld reduces patients’ pain during wound-care sessions by up to 50%, as well as reducing pain-related brain activity.