There are 2 ways to reproduce the bug
*1*
-Remove NVG's from the inventory (http://i.imgur.com/VLTPgkt.jpg)
-Night vision still works, because there are binoculars in the inventory (http://i.imgur.com/LLIhH3a.jpg)
-As soon as you remove binoculars from the inventory, night vision stops working. (http://i.imgur.com/g6gPX3o.jpg)
*2*
-Remove binoculars from the inventory (http://i.imgur.com/8hFj9GC.jpg)
-Remove NVGs from the inventory (http://i.imgur.com/w1D2ay2.jpg)
-Night vision still works, even without either NVGs or binoculars. (http://i.imgur.com/w1D2ay2.jpg)