Dayton Busse

Hey! Sorry if this is way too late but I also wanted to create this effect and figured it out! This effect is known as "cateye" bokeh or Optical Vignetting. Unfortunately, there's no good way to achieve this using the Physical Lens VOP node.

What you can do instead is implement what is shown at this link [www.creativeshrimp.com]. It's for Blender, but the setup in Houdini is essentially the same. I created a plane with a hole cut out and then used a single xform prim to move both the plane and camera with the same values. You can then play with the plane's scale and z-position to make the cateye effect more apparent.