  Exceptional points (EPs) with a global collapse of pairs of eigenfunctions
are shown to arise in two locally-coupled and spatially-extended optical
structures with balanced gain and loss. Global collapse at the EP deeply
changes light propagation, which becomes very sensitive to small changes of
initial conditions or system parameters, similarly to what happens in models of
classical or quantum catastrophes. The implications of global collapse for
light behavior are illustrated by considering discrete beam diffraction and
Bloch oscillation catastrophe in coupled waveguide lattices.
