The residents of Brevillier Village love living there. The retirement community in Erie, Pennsylvania overlooks Lake Erie, and paths dotted by benches follow the shoreline. The location provides beautiful views, and a grave threat: Just beyond the fence at the edge of the property lies a cliff that plunges 30 feet to the water below.

Compounding the danger, elderly residents with progressing states of dementia live in the building closest to the cliff. To protect them from harm, Brevillier adopted technology more common in sci-fi thrillers than homes: iris scan recognition.

A biometric that most people associate with a particularly grisly scene in Minority Report makes a lot of sense for elder care. Keycodes can be hard to remember, and difficult to tap into a keypad if you suffer from tremors or poor eyesight. Fingerprints might work, but your skin thins as you age, making prints harder to read. Plus, a weakened immune system increases the microbial hazard of key pads and fingerprint readers. All of which makes unlocking a door with your eyes pretty handy.

Iris scanners have been popping up at ATMs and airports, in hospitals and police stations, and even on mobile phones lately. And if the 300 residents of Brevillier Village are lining up to have their eyeballs scanned, the rest of you can’t be far behind.

Brevillier Village installed the iris scanners last fall, making it the first retirement home in the US to use the technology. Most residents come and go as they please after gazing into a scanner, but anyone with cognitive impairment must ask someone to open the door because their irises aren't in the system.

An iris scanner essentially slices the eye in half. An algorithm bisects an infrared snapshot of your eye vertically, from the edge of the white part to the pupil, unwrapping the iris into a flat, rectangular plane. Then it looks for places of high contrast—locations where microscopic melanin pigments are clustered—and measures the distances between them and the ends of the rectangle. The average iris scan collects more than 200 of these contrast points and stores them as a unique digital map.

All scanners work on this principle, and run on some variation of the system University of Cambridge mathematician John Daugman developed and patented in 1994. Until a few years ago, only a couple of companies held the rights to this technology, limiting the uses beyond law enforcement. But Daugman’s patent expired in 2011, giving rise to all kinds of new applications.

Scott Kimmel founded BioClaim, a company that helps hospitals and insurers use biometrics to reduce fraud. He says more than 20 million patients have volunteered to include an iris scan in their electronic health records, and sees it becoming more common. Instead of handing over your driver’s license and insurance card at your next doctor’s appointment, you’d step up to a scanner. This could go a long way toward minimizing mix-ups, because healthcare researchers estimate that as many as 10 percent of patients are routinely misidentified during medical record searches.

“We’re trying to make it about who you are versus what you carry or what you know,” says Mark Clifton, CEO of Princeton Identity. “You are the password.” The biometric tech company, made the system Brevillier Village installed, and the technology Samsung included in the Galaxy S8 smartphone and the S7 before it.

Smartphone iris scans seem much more plausible now that people don’t think twice about unlocking a phone with the touch of a finger. And it could improve security: Biometric security methods do a better job of preventing unauthorized access than credentials like a social security number or PIN. But critics note that once you've scanned your iris, it becomes a digital file that thieves can steal like any other data—and you can't replace an iris like a lost insurance card. That said, turning a stolen digital file into a 3-D copy of an iris remains an expensive and time-consuming proposition. “Biometric-based recognition does really raise the bar for hackers and terrorists,” says Anil Jain, a computer scientists and computer vision researcher at Michigan State University.

None of the iris scans at Brevillier Village are linked to medical records or financial accounts, so residents have little reason to worry about hackers or identity thieves. And surrendering a bit of privacy could keep them safe. Brevillier Village plans to tailor the system in the future by allowing some dementia patients greater access at different times of day. As a patient's health declines, administrators could limit their access rather than move them to another building. Studies have shown that seniors with dementia do better not only when they’re surrounded by more cognitively competent peers, but also when they can remain in a familiar setting. So for them, iris scans aren’t just a way to stay alive longer, they’re a way to thrive longer.