  A significant population of nearby stars have strong far-infrared excesses,
now known to be due to circumstellar dust in regions analogous to the Kuiper
Belt of our solar system, though orders of magnitude more dense. Recent sub-mm
and mm imaging of these systems resolves the circumstellar dust and reveals
complex structures, often in the form of rings with azimuthal non-axisymmetric
variations. This structure might well be due to the presence of embedded brown
dwarfs or planets. We have carried out deep adaptive optics imaging of two
nearby stars with such asymmetric dust: Epsilon Eridani and Vega. Ten and seven
candidate companions were seen in and near the dust rings of Epsilon Eridani
and Vega respectively, but second-epoch proper motion measurements indicate
that all are background objects. Around these two stars we can thus exclude
planetary companions at spatial scales comparable to the radius of the dust
structures to a level of MK=24, corresponding to 5 Jupiter masses, for Epsilon
Eridani, and MK=19-21, corresponding to 6-8 Jupiter masses, for Vega.
