Here's what my friend says. He works in the industry:

[Oakley uses exclusively polycarbonate (PC) lens material. PC has all sorts
of chromatic aberration. In other words: distortion. I've never been a big
fan of PC lenses and have always felt Oakley charges way too much for the
product you get. And personally never thought they fit that well.

For the Rudy Project Swifty the lenses are made from polyurethane (PU),
nearly as clear as glass. It is a very good material and does not have the
chromatic aberration of PC. Also the Rudy Project frames are a better
quality and my bet would be it would fit better. If wear either of the
Oakley or the Rudy Project all day his eyes would feel better wearing the PU
lenses.]