  The propagation of light in area metric spacetimes, which naturally emerge as
refined backgrounds in quantum electrodynamics and quantum gravity, is studied
from first principles. In the geometric-optical limit, light rays are found to
follow geodesics in a Finslerian geometry, with the Finsler norm being
determined by the area metric tensor. Based on this result, and an
understanding of the non-linear relation between ray vectors and wave covectors
in such refined backgrounds, we study light deflection in spherically symmetric
situations, and obtain experimental bounds on the non-metricity of spacetime in
the solar system.
