  {Using two different approaches, we study imaging in the strong lens regime
taking into account the effects of plasmatic environments on light propagation.
First, we extend the use of a perturbative approach that allows us to quickly
and analytically calculate the position and shape of the images of a circular
source lensed by a galaxy. Such approach will be compared with that obtained
from the numerical solution of the lens equations. Secondly, we introduce a
3-dimensional spheroidal model to describe the spacetime associated with the
dark matter halo around the lens galaxy and an associated optical metric to
incorporate the presence of the plasma medium. The (chromatic) deformation on
caustic and critical curves and associated multiplicity of images is also
analyzed for particular configurations.
