The arrival of TeV-energy photons from distant galaxies is expected to be affected by their QED interaction with intergalactic radiation fields through electron-positron pair production. In theories where high-energy photons violate Lorentz symmetry, the kinematics of the process gamma + gamma arrowright e super(+) + e super(-) is altered and the cross section suppressed. Consequently, one would expect more of the highest-energy photons to arrive if QED is modified by Lorentz violation than if it is not. We estimate the sensitivity of Cherenkov Telescope Array (CTA) to changes in the gamma-ray horizon of the Universe due to Lorentz violation, and find that it should be competitive with other leading constraints. gamma ray