  We study null geodesic congruences (NGCs) in the presence of spacetime
torsion, recovering and extending results in the literature. Only the highest
spin irreducible component of torsion gives a proper acceleration with respect
to metric NGCs, but at the same time obstructs abreastness of the geodesics.
This means that it is necessary to follow the evolution of the drift term in
the optical equations, and not just shear, twist and expansion. We show how the
optical equations depend on the non-Riemannian components of the curvature, and
how they reduce to the metric ones when the highest spin component of torsion
vanishes.
