I have seen the eye upon the Fool's bag - but it is much more clearly expressed upon the BOTA deck. On all versions of the Waite deck I have, the 'button' looks far more like a button.
Given the similarity of the Waite and BOTA deck, and not having the benefit of having Pollack's The Illustrated Guide to the Tarot, I cannot see what you see.
For the record, the BOTA deck takes each card (in most Cases from the RWCS) and adds minutia of detail, or clarifies details somewhat ambiguously presented. For example, on the Fool card, the Shin is up-righted, the eye on the bag is clear (as is the Eagle's head), the Flame over the region of the heart is clearer, and the 'folds' below the neck are clearly rendered with the tetragrammaton (ie, the four - Greek 'tetra' - lettered name of God in Hebrew: YHVH).
Are you sure the depiction mentioned, then, is not the BOTA's version?
It should also be noted that even in the early printed decks, there are, apparently, some minor variations - though I did not think that this was one of them.