The startup that wants to give surgeons X-ray vision

“Have you ever seen a spine surgery before?”

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Over Zoom, James Hu asks me this sincerely, standing in the middle of a large white room that reads between clinical and stylized. I consider the question, not because I have, but because it occurs to me: I’ve perhaps never thought much about it at all, and suspect many people haven’t. But it’s a medical phenomenon—and a surgical tightrope.

Hu, a doctor and cofounder of surgical precision access and visualization platform Illuminant, breaks it down: The spine is a high-wire part of the human body, where even infinitesimal mistakes can be disastrous. He demonstrates for me on a dummy.

“If you go towards the middle, that’s the spinal cord, and if you hit that, the patient is paralyzed,” Hu gestures. “And if you drive the needles a little too deep here, this is your aorta, this is your vena cava, and you can bleed out on the table.”

A few millimeters are the difference between success and failure, life and death. In the U.S. each year, spine surgeons are performing about 1.2 million of these high-stakes procedures. And Hu and his former Stanford classmate Eldrick Millares are building tech that, in some sense, helps those surgeons see. Their startup Illuminant is building a smart surgical lamp called Skylight.

“What Skylight does is display images directly on a patient’s skin to tell you exactly what’s underneath as you’re cutting,” Millares said. “You can basically get X-ray vision. It’s like a live tattoo that moves with the patient. It updates in real time, tells you exactly where you need to cut, the angle you need to go, and how deep you need to go.”

Illuminant—founded in 2021—has raised an $8.4 million seed round, led by Wing 2 Wing Ventures, Fortune has exclusively learned. The Los Angeles-based startup has taken a unique approach to fundraising: The company has additional venture backers (like Elderberry Ventures and Soma Capital) but about half of that $8.4 million is grant funding from federal institutions like the National Science Foundation, the National Cancer Institute, and the National Institute on Aging.

Millares and Hu have specifically chosen L.A., seeking to tap into the market of engineers who not only work in tech, but engineers who’ve come from entertainment. Their task is scientific, medical, and technical, but it’s also fundamentally visual.

“Disney Imagineering has this project where they project clothes on performers while they’re onstage, and you can change the clothes out,” Millares said. “We now have one of those folks here working with us—we’re projecting anatomy on patients.”

It often makes sense to start with the hardest thing, and spinal surgery is impossibly hard: One in five spine surgeries needs a revision.

“The future of spine surgery, and really any surgery that relies on navigation, is moving toward more precise and less invasive procedures,” said Dr. Jeffrey Wang, co-director of USC’s Spine Center and Illuminant’s clinical advisor, via email. “Over time, that also has the potential to expand where these kinds of procedures can be performed, not just in major centers.”

Spinal surgeries are the proof point (Hu also reckons it’s a sizable market, worth around $2 billion). Millares and Hu are looking at using Illuminant’s tech for lung cancer biopsies and other percutaneous access procedures (where tools like stents or catheters are inserted through a tiny, needle-made hole—the tech can also guide needle placement). Their eventual hope is grander: That most massive, open surgeries fade into medical history, like the surgical bone saws of the Victorian era.

“I think open surgeries are going to become more and more of a rare procedure,” Hu said, “limited to extremely complex cases, and all your bread-and-butter cases will be done percutaneously, through the skin.”

See you tomorrow,

Allie Garfinkle

X: @agarfinks

Email: alexandra.garfinkle@fortune.com

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