Patient states that Image size seems larger with the new RX....
3PM SV Sph Poly AR
-3.25
-4.50
Same PD
Old pair 0.25 less in CR39 plastic frame
Thoughts
Patient states that Image size seems larger with the new RX....
3PM SV Sph Poly AR
-3.25
-4.50
Same PD
Old pair 0.25 less in CR39 plastic frame
Thoughts
Perhaps the new frames are sitting closer than the old pair? The decrease in vertex distance will magnify the image a bit. Was there a significant change in base curve between the two? There shouldn't have been, unless the old pair was intentionally altered. If the base curve increased significantly, again you would get additional magnification over the old Rx.
The change in index isn't significant enough to cause any noticeable change in magnification, so I don't think that's the culprit.
Last edited by TheRobotious; 12-28-2014 at 05:38 PM.
If its not a BC issue, Maybe the patient is seeing just a little bit bettr, and hence "bigger"
BC are flatter if any different.
Frame might be closer but I moved it further away a bit.
Added AR so Doc might be correct....
Patient is the clothe designer and really bothered by this size difference.....
The only other option you have is to remake in a higher index. The increased index will cut the thickness back, both of which will help reduce magnification, but I'm not sure that will be so effective given that the old lenses were CR-39, so it's not like they've come from a 1.67 or anything.
It seems like the patient might be 'creating' at least some of the magnification, as proposed above.
This is a minus RX, there will be almost no reduction in lens mag with a 'thinner' lens, given that the central thickness will be fairly consistent. If it was the opposite of this rx, then that would be spot on.Originally Posted by TheRobotious
Ask them to look at their wallet. Is it bigger? Say "you're welcome" and schedule their two year appointment immediately. But seriously - if ever there was a "two-week tonic" case this is it. New Rx's are supposed to seem different -that's why it's recommended so frequently. Imagining an isekonic issue for minus lenses with such a mild Rx change might be a red herring.
Best answer I've heard so far.
Jawohl. Spot on.
You could always use the W. O. W. H. technique (Wipe Off With Heat). Take them in the back room, work on them for 15 minutes, heat them well and wipe them off really well, maybe increase the faceform a little, then return them to the face while still warm.
In addition to this, I also like to bang some tools around on the bench so they can hear I'm working hard on the solution.
Caroline, L.O.
If you suffer from severe nonlinear waterfowl issues, you don't have your ducks in a row.
Check for unwanted BU prism (tabletop looks convex).
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
bu ou?
see this for some cool info: http://drdrbill.com/downloads/optics...nification.pdf
thats what she said
happy new year
Yup, yoked prism. Look for differences between the new and old eyeglasses. It may be a contributor, along with the flatter BCs and somewhat closer fit/reduced back vertex distance.
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
Why changed to poly? Lose the poly AND the problem.
Thanks!
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