The Relevance of the Cosmological Constant for Lensing
  This review surveys some recent developments concerning the effect of the
cosmological constant on the bending of light by a spherical mass in Kottler
(Schwarzchild-de Sitter) spacetime. Some proposals of how such an effect may be
put into a setting of gravitational lensing in cosmology are also discussed.
The picture that emerges from this review is that it seems fair to assert that
the contribution of $\Lambda$ to the bending of light has by now been well
established, while putting the $\Lambda$ light-bending terms into a
cosmological context is still subject to some interpretation and requires
further work and clarification.
