  How does the appearance of a strongly lensed system change if a gravitational
wave is produced by the lens? In this work we address this question by
considering a supermassive black hole binary at the center of the lens emitting
gravitational waves propagating either colinearly or orthogonally to the line
of sight. Specializing to an Einstein ring configuration (where the source, the
lens and the observer are aligned), we show that the gravitational wave induces
changes on the ring's angular size and on the optical path of photons. The
changes are the same for a given pair of antipodal points on the ring, but
maximally different for any pair separated by $90^{\circ}$. For realistic
lenses and binaries, we find that the change in the angular size of the
Einstein ring is dozens of orders of magnitude smaller than the precision of
current experiments. On the other hand, the difference in the optical path
induced on a photon by a gravitational wave propagating \textit{orthogonally}
to the line of sight triggers, at peak strain, time delays in the range $\sim
0.01 - 1$ seconds, making the chance of their detection (and thus the use of
Einstein rings as gravitational wave detectors) less hopeless.
