Here's hoping that Thror's treasure had a Keurig or something.
The Book: No such scene occurs.
What difference does it make? Showing Smaug's eye has no impact on the rest of the plot. It stands to reason that, at some point in the novel, the dragon opened his eyes.
My Opinion: I remember being a little surprised at how much gold, exactly, Smaug had in this scene. The book is never explicit with any solid number, but it's enough for the massive dragon to comfortably lay on. Tolkien's own drawing of Smaug has a much smaller pile of gold, but it's hardly fair to say that Peter Jackson's interpretation is wrong. The fact of the matter is, Smaug has a lot of money - a nearly unassessable amount.
This scene is awesome, and Smaug's eye looks amazing. Anybody who disagrees with this sentiment is objectively incorrect.