In high energy collisions of hadrons, processes with t-channel exchange of Pomerons or photons lead to final states with large rapidity gap. In this talk, we will concentrate on the theoretical description of central exclusive vector-meson production, which is induced by the gamma-Pomeron fusion. Here, recent data by the LHCb collaboration give access to photoproduction energies at high energies not accessible in earlier experiments. We will also discuss dilepton production by gamma-gamma fusion. This process is of interest because it allows the calculation of
proton-dissociative processes almost model independently.