Here's where Chase starts to get clever. Each time the diner's door opens, its bell rings and we see Tony looking up in the direction of the noise. In the following shot we see whomever's coming through the door from Tony's point of view - or through his eyes, if you like. The bell establishes a pattern of shots and elicits from us a Pavlovian response. We learn to anticipate the sequence: the bell rings, Tony looks up, and we know that whatever immediately follows those raised, expectant eyebrows is whatever Tony is seeing at that exact second. Ding, raised brows, eyes, ding, raised brows, eyes.
....
Meadow finishes parking, and we see her dashing towards the diner. Any second now we know she's going to push through that door, and the ding, raised brow, eyes sequence is going to repeat itself. So when that bell dings - or perhaps tolls - for the final time, and we see Tony's eyebrows and then... nothing... nothing... we're forced to conclude that this 'nothing' is what Tony is seeing at that exact moment. And under what circumstances other than death would a man's point of view change so swiftly and unexpectedly to nothing? To blackness?