A Hero Behind the VR Headset

Walter Greenleaf won’t stop until virtual reality and extended reality reach their full potential in health care.

In 1985 when Walter Greenleaf received his PhD in neuroscience from Stanford University, he did something unimaginable. Rather than building or joining a prestigious research lab like his esteemed colleagues, he joined his friend Jaron Lanier’s startup, convinced that an emerging technology — virtual reality — could prompt a renaissance in medicine. He received a lot of pushback in his academic circles. “It was like I was leaving the church,” says Greenleaf, laughing about it today. “People thought I was a heretic.”

Though many of his colleagues refer to him as the “godfather” of therapeutic virtual reality, he’s uncomfortable with the attention. “Call me Walter,” he says, which is part of his disarming charm. His ability to distill complex technology and academic jargon has everyone from NASA to major health systems, the largest U.S. health insurer,, and startup founders seeking his counsel. His deep medical knowledge and long history in VR is utterly unique.

Much of that growth will be due to the simple fact that VR devices are increasingly interactive and affordable, and many now have integrated sensors. They can collect that sensor data for users or doctors, giving them a more comprehensive window into the everyday metrics of people’s health. “We have voice analytics capable of scoring tone as a biomarker for anxiety and depression that can also offer us clues about pain,” says Greenleaf. “Voice, movement, facial expressions, psychophysiological data like heart rate, variability, and EEG, gaze direction — all this data is going to help us do so much more than we’ve been able to do before.”

While health care applications of VR have become a growing trend among emerging technologies in recent years, Greenleaf has been a pioneer from the very beginning. “What’s interesting is Walter sees how much potential there is using these technologies not just to redefine care, but to redefine human interactions with the health care system,” says Brendon Hale, the chief research scientist leading the digital therapeutics research team at UnitedHealth Group, the world’s largest health insurance company.

Greenleaf hasn’t just nurtured and steered the virtual reality ecosystem — he also actively sought to protect some of its key patents.

VPL collaborated with Mattel for a while, but cash flow limited product development. In the early 1990s, VPL Research partnered with Thomson-CSF, a military contractor partly owned by the French government. Strapped for cash, Lanier put the company’s entire intellectual property portfolio up as collateral on some small bridge loans from Thomson. By the mid-90s, with the advent of the internet, the world became obsessed with web surfing, and VR faded from the limelight.

In 1993, VPL Research was forced into bankruptcy by its largest shareholder in what appeared to be an attempt to grab ownership of the patent rights. However, five years earlier, Lanier had licensed medical rights to VPL’s patents to his friend, Walter, who refused to let Lanier’s company and its portfolio of fundamental VR patents and intellectual property revert to the French military contractor Thomson-CSF. Instead, he spent years defending a series of virtual reality patents until he could initiate a deal for Sun Microsystems to acquire the patent portfolio. “It took a lot of time and costly legal fees, but I was able to put together a deal with Sun Microsystems to obtain the IP with the goal of having Sun work to move the field forward,” says Greenleaf. “Of course, twenty years later, the patents have all expired.”

By protecting access to the patents, Greenleaf didn’t just bail out the fledgling technology — he helped secure the future of virtual reality.

United Healthcare’s Hale agrees. “The health care system is largely reactive and doesn’t have the ability to take into account someone’s entire medical situation. What’s so interesting about the VR and XR space is that we get an authentic understanding of the world you’re seeing and how you, as an individual, react to your world [in a way] not fully realized with 2D technologies,” he says.

“It frustrates me that the health care system only interacts with humans when they’re sick,” says Hale. “However, what excites me is the opportunity to move health care beyond episodic interactions with patients to a more full-spectrum understanding of their health and their environments so that we can deliver personalized care.”

Four years ago, in Burlington, Vermont, Aaron Wisniewski had been obsessing over an idea so simple, he questioned it himself. What if adding scent to VR could increase immersion?

Like many others in the field, he looked to Greenleaf for advice. “When I decided to start my business, I went out to Stanford to try the technology and to understand Walter’s vision on how VR was going to change health care radically,” says Wisniewski. “Not in a grand, dreamy way, but tactically. He explained where VR is already making a difference, who the players were on the technology side, who were driving outcomes on the industry side, and who the adopters are.”

Like every entrepreneur, CEO, or scientist interacting with Greenleaf, Wisniewski loves talking about his friend, collaborator, and mentor. “In the VR solar system, Walter’s the sun. He gives light to all of us and keeps us elegantly orbiting and traveling in the right direction,” says Wisniewski. “He guides us, keeping us in the right proximity to each other without collisions.”

When Greenleaf talks about the future of VR in health care applications, he is most excited about companies like Penumbra, for which he serves as an advisor. It is attempting to harness the power of VR to enhance the neuroplasticity of the brain.

With no background in gaming and wearing a suit jacket, Elsesser felt out of place. Sixense’s team put a headset with an attached battery pack tethered to a computer on him. “In the middle of playing that game, I heard two voices urgently yelling above the soundtrack coming from the game,” says Elsesser. “Close your eyes, close your eyes!” The battery was slipping, and Sixense’s employees were worried some of the imagery would disappear. Wanting to know what he was missing, he kept his eyes open. The floor of the castle that he was standing on went bright white. “I got a little unbalanced because I felt like I was falling, and then I fell,” says Elsesser. “I physically fell to the ground in my suit in front of everyone.”

After his first VR experience, Elsesser asked himself how Penumbra could use that same technology.

“At that moment, after years with my cofounder, a neurologist, I realized that if you can trick my brain to have that physical reaction, we are sitting on the magic tool to trick other people’s brains into recovering function in different settings,” Elsesser says. “The fundamental principle of stroke rehab is based on tapping into neuroplasticity to rewire the brain. If you can do that in virtual reality, you can tap into that concept and accelerate that function.”

When Elsesser and his partner started Penumbra, they believed they could help several hundred thousand people in the United States affected by strokes. When they expanded their products to other indications, they saw an opportunity to help almost a million people. “When you look at the number of people we can help using therapeutic VR across the entire spectrum — mental health issues, memory, managing pain, the physical rehab work, and beyond — you’re looking at tens of millions in the U.S. alone. Why wouldn’t we try to do that?”

“We can shift attitudes and behaviors if we can activate the power of the brain’s reward system. This allows us to activate neuroplasty changes and reinforce behaviors and learning,” says Greenleaf. “Because of VR’s ability to immerse us in somebody else’s point of view, we can facilitate empathy.”

Similarly, when a patient is discharged from a hospital, rather than handing them a stack of take-home instructions, Greenleaf envisions a better scenario in which a clinician’s avatar can interact with, inform, and motivate their patients to make necessary lifestyle changes.

To Lanier, who’s equal parts visionary, artist, and nostalgic digital philosopher, Greenleaf’s impact on therapeutic VR isn’t surprising. “Back in the 80s, it was socially awkward in startup circles and unusual to see an academic, but Walter was the ultimate Silicon Valley cool cat.” Pausing, his expression turns serious. “The thing is — Walter is unquestionably the principal pioneer of all therapeutic applications of virtual reality.”

Hale agrees with Lanier. “What’s interesting is the reality that Walter has seen for decades,” says Hale. “We’re just now developing the technological capabilities to realize his vision. In many ways, the world is catching up with Walter’s mind.”

Editor’s note: This story was updated on 9/3/21 to correct the attribution of a quote in the 28th paragraph.

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