Officially, the purpose of the Eyes of the Empire is to spy on common people, particularly the people of Callow, and keep watch for any signs of rebellious sentiment or potential Heroes.
However, their actual purpose is not to gather any information at all. Instead, they are just there to pretend to be sneaky and watchful so that any rebels will assume that they are listening and feel safe as long as they know the (highly visible) Eyes are not watching them. Real Imperial spies much more convincingly disguised as actual commoners, allowing them to fit in with people who assume that if they have checked for tattoos they will catch any potential snitches.
Distinctive Marks Edit
The Eyes of the Empire have a special tattoo of a lidless eye somewhere on their bodies. They also tend to wear hoods that cover their faces.