Measuring and Setting IPD on VR Headsets for Surgical Simulations

The distance between your eyes is called interpupillary distance (IPD). This space varies from person to person ranging from 42 to 75mm with a mean average of 61mm for women and 63mm for men. Failure to properly measure and set IPD may result in blur, eyestrain, distortion and it might even make some people feel sick. In our VR surgical lab at Ghost Productions and various medical exhibition events, we’ve given hundreds of our visitors their first experiences in virtual reality and here’s how we ensure that each user has the best possible experience.

Seeing Double?

The distance measured distance between your eyes, is your IPD. Most stereoscopic devices, such as microscopes, binoculars, and VR headsets have the ability to adjust the distance between each eye’s viewport and this provides each user a custom fit. As a VR developer and evangelist, I’m often giving our clients their first experience in virtual reality. Should I fail to set the IPD correctly, their first experience might be terrible. So here’s how I set IPD for each person I introduce to VR to ensure they’ll come back for more.

How to Measure IPD

You can just put a ruler on their forehead but I’ve found that doing so provides inconsistent measurements. My preferred method to get fast and accurate measurements is by using a Pupilometer. https://olleyes.com/ makes some seriously high-tech versions or you can one up at Walmart for less than $40.

I recently tried a few apps on my iPhone designed to measure IPD and EyeMeasure works really well. To use this, all you have to do is point your screen at the face of your next VR victim visitor and it will scan their face and provide a measurement within about 0.1 +/- of Pupilometer measurements. Check it out on the iOS App Store. While I’m sure other apps exist are made for Android and other devices, I can’t comment on them because I’ve already sold my soul to Steve Jobs. Then it was inherited by Tim Cook according to Steve’s last will and testament. As a result, touchless faucets and automatic doors no longer detect my presence.

Setting IPD on the Headset

It used to be super easy to dial in on headsets like the Oculus Rift S and even the Oculus Quest 1. While the Quest 2 is a significantly more advanced piece of untethered VR hardware, it does suffer from a few devolutions. The headband and IPD adjustment have unfortunately reverted to the days when Lawnmower Man was the leading mainstream example of VR, circa 1990.

The method requires the user to take off the headset and physically grab one of the lenses and move it left or right until you feel a click. Yes, it feels like it will break off in your hand and yes, there are only 3 settings. 58mm, 63mm, and 68mm. If your IPD is 61 like mine, you are officially no longer considered a viable human by the Facebook Corporation. Unofficially, I’ve found that if you carefully move the lenses and get them to hang between the 3 established settings, I can dial in a better image.

It’s a pain in the digital derrière, but I did recently stumble across a patent filed by Sony on the Road to VR for an automated IPD adjustment so maybe in 5 years or so IPD will be a forgotten problem of the early VR era.

Here is a video playlist of tutorials on measuring and setting IPD on various devices.

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