Varjo is likely using either an eMagin OLED microdisplay with a 9.3 micron pixel pitch or a Sony OLED microdisplay with a 8.7 micron pixel pitch.
http://www.kguttag.com/2017/06/26/varjo-foveated-display-part-1/
https://www.wired.com/story/varjo-vr-microdisplay/
https://www.theverge.com/2017/6/19/15820336/nokia-varjo-virtual-reality-headset-microsoft
Scoble with Vargo CEO
https://www.facebook.com/RobertScoble/videos/vb.501319654/10155409511619655/
