With the explosion of smartphones has come an epidemic of selfie-taking. These mini self-portraits are now a currency we trade on Instagram, Snapchat, and Facebook. And they’re increasingly a way we see ourselves, and our flaws.

But sometimes what we see in selfies isn’t really what’s there, plastic surgeons are warning. That’s the takeaway from a new research letter published recently in the journal JAMA Facial Plastic Surgery.

Boris Paskhover, a facial plastic surgeon at Rutgers University and one of the authors of the paper, says patients have been coming into his clinic demanding nose jobs because they thought their noses looked too big in their selfies. The American Academy of Facial Plastic and Reconstructive Surgeons has noticed the trend too. According to a 2017 poll, 55 percent of facial plastic surgeons reported seeing patients who wanted surgeries to help them look better in selfies, up from 13 percent in 2016.

Paskhover right away recognized what was really going on with all the selfie nose job requests: “I’d say, ‘Your nose doesn’t look big — there’s distortion when you keep a camera close to your face,” he said.

To prove it, Paskhover and his co-authors set out to quantify selfie distortion using a mathematical model that takes into account how the distance between a person’s face and a camera lens can change their facial features in a photo.

They found that when the lens is very close to the face — about 12 inches — it makes the nose look about 30 percent larger compared to the rest of the face. You can see that difference below in the photo taken at selfie distance (12 inches) on the left versus regular portrait distance (60 inches) on the right:

The reason for the distortion is pretty simple: It’s all about perspective — and how what we see changes depending on our distance from an object. When you’re standing right in front of a building, for example, it looks larger because it’s very close to you, while the buildings around it of the same size look smaller in the background. When you step back a mile, all the buildings in front of you will look about the same size.

The same thing happens to your face in photos, Paskhover said. When a camera lens is very close to your face, your nose is nearer to the camera relative to the rest of your face, and will therefore look larger. But when you step away from the camera, the relative distance between your nose and the rest of the face flattens — making your nose appear more proportionate.

“If all the pictures [you take] are up close, the way you view yourself may be distorted,” Paskhover said. “Realize [selfie view] is skewing how you look.”