  We improve the calculations of the $\eta \to \pi^0 \gamma \gamma$ decay
within the context of meson chiral lagrangians. We use a chiral unitary
approach for the meson-meson interaction, thus generating the $a_0(980)$
resonance and fixing the longstanding sign ambiguity on its contribution. This
also allows us to calculate the loops with one vector meson exchange, thus
removing a former source of uncertainty. In addition we ensure the consistency
of the approach with other processes. First, by using vector meson dominance
couplings normalized to agree with radiative vector meson decays. And, second,
by checking the consistency of the calculations with the related $\gamma \gamma
\to \pi^0 \eta$ reaction. We find an $\eta \to \pi^0 \gamma \gamma$ decay width
of $0.47\pm 0.10$ eV, in clear disagreement with published data but in
remarkable agreement with the most recent measurement.
