They've had a device dubbed "the voice of God" that can put voices into peoples heads at a distance at least since the 1980's. I think it used microwaves back then, with expected side effects on the target. It makes sense that they'd use a computer to dispense operant conditioning covertly, but I doubt they can actually see the output of someones optic nerve covertly. They probably are just looking at all the screens a target looks at.