Evaluate Near power or ADD power for Freeform products?

[Delly]

I think estimation of near power is more strict than that of ADD power. Because later one ignore cylinder tolerance and axis tolerance for near power. ADD power only indicate different mean between distant power and near power. I wonder what standard you choose at your market.

Another question, why is axis so different between distant cylinder and near cylinder? Which one is real axis wearer need? Or Is axis changed when wearer see things from distance to near?

Thank you.
Best regards,
Delly

[Delly]

Oh~ no one reply to me. Is anybody help me? Thank you.

[essegn]

Another question, why is axis so different between distant cylinder and near cylinder? Which one is real axis wearer need? Or Is axis changed when wearer see things from distance to near?

I suppose you are talking about cylindrical prescription - not unwanted cylinder.
If you use the progressive's calculation without atorical optimalization the cylinder axis differs a bit for distance and near vision (the difference is app.2-10 degress)
If you use the progressive's calculation with atorical optimalization the cylinder axis differs significantly for distance and near vision and also cylinder power changes slightly
the same is for individual prescriptions..

The answer is that both axis (at distance portion and near portion) are the real that wearer needs.

I can't explain why - i would be question for design creator. Find the commercial page at this web - IOT, ask maybe you will get a proper answer.

[Uncle Fester]

Optiboarder and Carl Zeiss engineer Darryl Meister has a great article on progressives and I think some of your questions are addressed in the section "Viewing Zone Configuration" and "Design of Periphery" about 3/4 down from this tutorial:

http://www.opticampus.com/cecourse.p...essive_lenses/

I hope this helps. :)