You can control what to retrieve from an Adobe Illustrator file.
Note:
Only up to Ilustrator version 8 is supported.
By setting File > Import > File 
Illustrator options, you can enable Alias to import the geometry as a Group of curves or as individual curves. You can also Scale the image before importing it into Alias.
When saving an Illustrator file choose File > Export > Illustrator. Free curves, isoparms, surface edges, trim edges, and curves-on-surface are exported as degree 3 Bézier curves in Illustrator. An Adobe Illustrator version 8 file with the .ai extension is written.