Who would want ink injected into their eye?

Jason Barnum, 39, who pleaded guilty to the attempted murder of a policeman, has ornate tattoos on his head and part of his face - teeth on his cheek, an eyeball in middle of his forehead. But even more dramatically, the white of his right eye has been tattooed jet black. Arguing for the prosecution, Anchorage Police Department Chief Mark Mew urged the judge to take a look at Barnum's face which, he said, showed the convicted criminal had "decided a long time ago that his life was about being hostile to people".
 But, in tattooing his eyeball, was Barnum really expressing hostility to the rest of society?
And if our eyes really are the window to our soul what else might a tattooed eyeball say about its owner?