I present the renormalization group improved collinear
resummation of the photon-gluon impact factors.
We construct the resummed cross section for virtual photon-photon
($\gamma^*\gamma^*$) scattering which incorporates the impact factors
and BFKL gluon Green's function up to the next-to-leading logarithmic
accuracy in energy.
The impact factors include important kinematical effects which are
responsible for the most singular poles in Mellin space at
next-to-leading order. Further conditions on the resummed cross
section are obtained by requiring the consistency with the collinear
limits. Our analysis is consistent with previous impact factor
calculations at NLO, apart from a new term proportional to $C_F$ that
we find for the longitudinal polarization. Finally, we use the
resummed cross section to compare with the LEP data on the
$\gamma^*\gamma^*$ cross section and with previous calculations. The
resummed result is lower than the leading logarithmic approximation
but higher than the pure next-to-leading one, and is consistent with
the experimental data.