  We investigate the propagation of light rays and evolution of optical scalars
in gauge theories of gravity where torsion is present. Recently the modified
Raychaudhuri equation in the presence of torsion has been derived. We use this
result to derive the basic equations of geometric optics for several different
interesting solutions of the Poincar{\'e} gauge theory of gravity. The results
show that the focusing effects for neighboring light rays will be different
than general relativity. This in turn has practical consequences in the study
of gravitational lensing effects and also determining the angular diameter
distance for cosmological objects.
