I would say that if Opticians want to refract they should have to do some schooling for it. If optometry school is four years, part of it is understanding the science behind refracting. I'm sure most opticians would not enjoy taking a calculus based physics. I personally found my physics class like that very helpful. I think certain on the job training is useful, but that can only go so far. Almost all my engineers friends understand all the optics because they have the schooling and almost all my coworkers don't. Now if there was only a way to convince my friends to take a pay cut, I think I could make them good opticians.