Kuiper Belt and Oort Cloud Objects: Microlenses or Stellar Occulters?
  The occultation of background stars by foreground Solar system objects, such as planets and asteroids, has been widely used as an observational probe to study physical properties associated with the foreground sample. Similarly, the gravitational microlensing of background stellar sources by foreground mass concentrations has also been widely used to understand the foreground mass distribution. Though distinct, these two possibilities present two extreme cases during a transit; At the edge of the Solar system and beyond, the Kuiper belt and Oort cloud populations may present interesting foreground samples where combinations of occultation and lensing, and possibly both during the same transit, can be observed. To detect these events, wide-field monitoring campaigns with time sampling intervals of order tenths of seconds are required. For certain planetary occultation light curves, such as those involving Pluto, an accounting of the gravitational lensing effect may be necessary when deriving precise physical properties of the atmosphere through the associated refraction signal. 
Asantha Cooray