X, Y, and Z

[drk]

OK, essilor reps seen today. There has been, I've noted, a foray into "depth of focus" a lot, lately.

For context, we've had EDOF ("extended depth of focus") technology FOREVER, but we've been calling it aspheric multifocal contacts. Unilens, Conforma and David Volk started it before my time, and B&L bought it (I think that's right). Essentially it's a "low asphericity" conical section multifocal and they use the daylights out of it in RGPs and SCLs, now.

THEN the big hot thing was to incorporate it into IOLs, and after decades, ophthalmology is touting how great EDOF is. (Yawn. But correct.)

SO NOW recently it seems that the lens companies are figuring out ways to make such asphericity part of the lens design. I don't understand--because of marketing mumbo-jumbo because apparently the reps are too stupid and we're too stupid to be talked to any other way--but it seems that some/all points within the corridor and near zone have extended depth of focus (due to this asphericity, I think). The benefit touted is that the patient has more play in depth of focus at a given head angle/lens location and won't feel such a need to look up and down the corridor.

The way I think of it, is that while Varilux has done quite a yeoman's job of smoothing out peripheral astigmatism in the X and Y coordinates (that is, on the lens surface) now they're smoothing in the Z axis, back-and-forth or "in-and-out".

Question 1: Anyone have insight on this?
Q2: Am I getting this right?
Q3: Does this work?
Q4: What would we give up? I'm thinking "soft focus = low contrast or less clear".

I'm pretty sure I've heard of this approach from Zeiss or Shamir, too?