For context a person has stolen a piece of junk military equipment that can allegedly "warp reality". Turns out to be a false rumor, the device actually has a limited ability to alter/warp visual perception within a localized area.
With context out of the way the device would work by scattering tiny particles into the air resulting in a very warped sense of vision. It would affect the human eye and other optical instruments used to record images such as cameras in the same way.
Vision would be blurry/smeared making it very difficult to do things like aim and/or walk properly for everyone (except the user of the device who is shielded from it's effects and can see normally).
It wouldn't completely obstruct vision as people within the area would still be able to distinguish faint shapes and colors, they just wouldn't be able to see properly enough to avoid confusion, nauseousness, dizziness.
My question how can I explain this in a semi-plausible fashion ? (be it in scientific or pseudo-scientific manner, if all else fails I have no problem with just going with magic)