Digital PAL Add calculations?

[juno]

Hey all, I just got a Camber job in (Walman's Power Plus branded one). It's got all the digital conversion values on the order sheet, looks more or less fine, until I get to the Add power. Pt is -7.00ish, some cyl at 90ish OU, and an add of 2.25. Normally when I get a job back with the digital conversions, it's not unusual for me to see that Add altered to like a 2.18, give or take. This one was dropped all the way to a 1.88 in both eyes. What kinds of factors would account for that dramatic of an alteration? It's a Daddy-O frame, and the other lens in a similar-ish frame is 1.98. I'm willing to trust the machines to calculate the math better than me, but I kind of want to know the WHY of that big a change

[drk]

Well, if you add +0.12, it's a +2.00 add, so it's really minimal, anyway. Not dramatic.




It's not a toomah.



In general, of course, more wrap in lenses = less need for x90 astigmatism correction in the lens itself, so you'd expect that effect.

If you tilt the lens on the horizontal axis (panto) it would add minus, so maybe the reverse is true in your case? Minimal pantoscopic angle for that thick old thing? P.S. that's a great sun Rx frame for those powers, but dang they don't adjust!