Virtual Reality 101: Why does IPD matter?

Shane R. Monroe
4 min readOct 4, 2019

Pupillary distance or interpupillary distance (IPD) is the distance measured in millimeters between the centers of the pupils of the eyes. Everyone is different and the value changes based on whether you’re looking at something close up or far away. But why does this matter to the virtual reality participant?

Image courtesy of https://endmyopia.org

Even if you’re not into virtual reality, you may be familiar with IPD as it is important in the positioning of the lenses in your eyeglasses.

The optical center of the lenses must be positioned correctly in relation to the center of your pupils or undesired results can ensue; such as eye fatigue and headaches.

The further your eyes shift from the optical center of the lens, the more the light hitting your retinas is going to be bent in various ways that aren’t going to be “right” — and this is what causes the aforementioned issues.

What’s even more crazy is that when you’re looking at something far away your IPD is greater than when you’re focused on something closer; your IPD is dynamic by a couple of millimeters.

Now that we have an idea what it is (a variable distance different on everyone) and why it matters (your well being!) — let’s apply this to virtual reality.

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Shane R. Monroe

I write, blog, record and review anything that interests me — including humanity, parenting, gizmos & gadgets, video games and media.