  Performing an nonperturbative path integral for the geometric part of a large
class of 2d theories without kinetic term for the dilaton field, the quantum
effects from scalar matter fields are treated as a perturbation. When
integrated out to two-loops they yield a correction to the Polyakov term which
is still exact in the geometric part. Interestingly enough the effective action
only experiences a renormalization of the dilaton potential.
