Sergio Muñoz said:I believe you are looking for a very comprehensive independant comparision of progressive lenses. Unfortunately such a project will require a great deal of time and the employment of very sophisticated technical equipment. The reason I say unfortunately is that all of this testing and evaluation must be paid for. If a national opticians association was to invest in such a study it could possibly be properly done without bias. I suspect the only way to fund such a project is from donations and these donations will likely come from lens manufactures who will put pressure either directly or indirectly on the results.Maybe I am wrong, but the wrost problem of all manufacturers and designers is the lack of transparency. The 'normal' optician demands to understand clearly why PAL x is much better than PAL y; and the only thing we can measure is the spherical values. We are totally bored of hearing the "swim" effect and the prismatic balance. Show us some kind of studies like Mr. Sheedy's one; even if it consider only the small piece of the cake. If it's truth you invest so many money in R&D you should have done it.
The proof by comparision that you are looking for in progressive is very complex for many reasons. One is the number of lens powers possible. Comparing all possible powers in a number of lenses is quite a challenge. Then there are variables in surfacing that would have to be considered. Example: One design may preform better when the surfacing is off by an amount within specs. while another one that is off power with specs may not perform as well.
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