There are a number of explanations why the photo may look like that. One reason may be that you think you were looking at the lens but that was not the lens. This can also be achieved if there was actually another camera taking your picture at the same time. Another reason would be that you momentarily shifted your eyes and moved back as the shot was being taken. Happens quite a lot, really. It may also be an optical issue – medical. Then again, the photographer may have intentionally duped you and took a shot when you weren’t looking.
Probably the worst thing you can do is stare into the camera as if you were facing a firing-squad.
Photographers use a number of tricks (the most obvious being to point the camera slightly to one side) to avoid this. An old trick I used was to trip the depth-of field preview (the subject is ALWAYS tensed up, waiting to hear a click) and then take the shot as the sitter relaxed.