In the first place, there are infrared LEDs which will frame the eyes as well as the nose areas, and taking into consideration how infrared lights happen to be totally invisible to human eyes, the glasses can be worn just like your standard issue glasses. Since these LEDs can be detected by cameras that are sensitive to that wavelength of light, the glasses will break up face detection. Not only that, retro-reflective materials will do their job by reflecting light back at the same angle in which it arrives.
Right now, this pair of privacy glasses remain a proof of concept, and neither do they look fashionable enough to wear outside and parade it, but it’s touted abilities are certainly something worth looking forward to.