The trick to surviving an open-plan office is to realize that everyone is paralytically distracted by anxiety for at least 75% of the time. This means that the other people aren't watching you; they're busy fretting about their own sense of being watched. It also relieves you of guilt for the low productivity that's typical of such spaces.
People in open plan offices aren't paralytically distracted by anxiety 75% of the time, or for any particular intervals of time. It's not nearly everyone, and what anxiety there is results from an accumulation of interactions and interruptions over time, much like how you shouldn't work in the same place you sleep.
