I've seen several posts referencing the eyes as some unknown race of aliens with their own agenda.
Personally, I've always thought that any being who keeps a consistent presence in/connection to cytospace (like when Spensa listens to the stars) is one of those eyes. And presumably every "civilized" race of aliens has any number of individuals logged into the cytospace at any given time. They may even designate some cyto-cops to take shifts looking for human cyto-activity. These would be the eyes specifically looking at Spensa.