Edge compressed bokeh

Using Camera Blur (or Frischluft LensCare), you can create bokeh effects pretty easily.

But I notice real bokeh can have distortion as you move away from the centrer of the lens. Sometimes it compresses into a "lemon" shape along the edges.

http://www.dyxum.com/dforum/tp-bokeh-studies_topic28088.html

The only thing I can think of is Particular/Form and a custom bokeh shaped particle emited from layer brightness? And maybe a radial gradient driving rotation?

Any other thoughts how to do this?