We employ a difference equation approach to study the Plancherel-Rotach asymptotics of q-orthogonal polynomials about their largest zeros. Our method for q-difference equations is an analogue to the turning point problem for Hermite differential equations. It works well in the toy problems of Stieltjes-Wigert polynomials and q-1-Hermite polynomials. We shall also explore the case when q is variable.

The paper is a joint work with Mourad Ismail.