GZK photon constraints on Planck scale Lorentz violation in QED

We show how the argument exploited by Galaverni & Sigl in Phys. Rev. Lett., 100, 021102 (2008) (see also arXiv:0708.1737) [1] to constrain Lorentz invariance violation (LV) using Ultra-High-Energy photon non observation by the AUGER experiment, can be extended to QED with Planck-suppressed LV (at order O(E/M) and O(E/M)). While the original constraints given by Galaverni & Sigl [1] happen to be weakened, we show that, when used together with other EFT reactions and the expected detection of photons at E > 10 eV by AUGER, this method has the potentiality not only to basically rule out order O(E/M) corrections but also to strongly constrain, for the first time, the CPT-even O(E/M) LV QED.