An information delivery device interacting with a user's eye, the device comprising an eye characteristic reader for reading at least one characteristic of the user's eye, a retinal projector for projecting information onto the retina, and an eye characteristic processor operative to receive at least one characteristic of the eye and to select the information based at least partly thereupon. A content protection system may comprise a multiplicity of such eye characteristic readers and a content protector receiving said at least one characteristic from such readers and controlling the user population's use of content to be protected based on that at least one characteristic. Related apparatus and methods are also provided.