I understand from several labs that specialize in DS FF progressives that they many companies are "tweaking/adjusting" their corridor designs after analyzing progressive redos and non-adapts.

It would appear that their is a statistically-significant correlation between the longer corridors (which we ECPs had formally thought were superior to "short" corridor versions) and redos/non-adapts.

Me thinks the following:

For years now, the fashion in eyewear has been all about narrow "B" rectangles. And we've apparently been "too" successful in using any number of conventiona, fixed but shorter corridor length progressives to fit into our client's frame fashion desires.

The good news is it worked.

The bad news is they've gotten used or developed habits favoring less eye depression angle.

This then are the reasons, I'm goning to speculate, behind the need to tweak the corridor length on the DS FF progressive algorithyms - especially the ones position to "fit" the progressive to the frame. This is important to appreciate, now that "B" dimensions are on the rise.

FWIW

Discussion?

Barry