Surface Finish Problems

I'm having surface finish problem cutting Intraocular lenses. I use a .230 mm 2 flute end-mill to profile the lens. The problem is that portion of the chip remains attached to the upper edge of the lens profile. This lenses are made out of a special type of acrylic, which is soft and gummy. My theory is that sometimes I get batches of material that are softer than others so that the end-mill does not shear at exit of the part, but rather pushes the material. I also noticed that the end-mill flutes are course (the cutting edge is sharp, though).

Any thought in this regard will be appreciated.