Doesn't really remind me of tunnel vision.  It seems very "digital" whereas tunnel vision is more "analog".  This is just a perfectly clean-edged square of blankness.  Plus it's a passive matrix, I didn't think those were susceptible to that.  I don't know much about these kinds of displays, but I guess it might be that there's a dead spot in the "grid" that means everything from that point on simply cannot display?  I couldn't really tell how it works from my disassembling of the screen.