Gearheads of War

My question is what is Solid Snakes Eye peice? Is it a super genetic patch that he got because he lost his eye. Now im not so sure about that, because in all the screen shots i've seen he always has it on his left eye.

http://img235.imageshack.us/img235/8427/img12832mgs42yw7.jpg

observe in this picture his eye patch is on his left eye. However on the box for MGS4 he has no patch

http://www.gamepro.com/sony/ps3/games/news/images/174948-1.jpg

Now on teh gamespot page for MGS4 there are two pics where one he has the patch on his right eye and then another is on his right. The pics right next to the Name

http://www.gamespot.com/ps3/adventure/metalgearsolid4/index.html?om_act=convert&om_clk=topten&am p;tag=topten;all;title;8

So obivously it must be something other than Snake lost his eyeball, so again with the question

What the hell is it?