Psychic Warrior by Bob Mayer andaka Robert Doherty. Read it a few times, almost certain this is the one you are looking for.
It's set in 1981 and opens with military psychics attempting to "remove-view" Russian sites. After it doesn't work, Project Grill Flame is shuttered, at least officially. Off the books, it was renamed Bright Gate, and is dedicated to create a "virtual soldier" who can leave his body and act using only his mind. Unfortunately, the Russians have their own project, and their assassin, Chyort, "Devil," is in action. The protagonist is Sergeant Major Jimmy Dalton, a former Green Beret (or possibly a Ranger. The synopses disagree on the point) with no family ties who leads a team of Psychic Warrior. There was a sequel, Project Aura, which introduces a set of villains named the Priory.
It was released in 2000, so it would just barely squeak in for your 15 year range.
Cover images for the first and second books:
Confirmation of the optic nerve connection in the Russian subjects:
Each of the four men was horribly disfigured. All four were blind, their eye sockets empty, the gaping holes red and scarred. On each man’s head four metal sockets extended out, having been surgically implanted through the skull directly into the brain. It had taken the scientists at SD8 many years to perfect the technique of implanting those sockets and to determine the correct location for each.
