Hello everybody
I have faced several cases of patients who had to rises his glasses, in order to reach the maximum clarity of near vision area. The patient are always with plus powers.
The last case is:
Recipe:
Sph. +2.50 Add. 2.50
Progressive:
Free form with individual calculations and 12mm. corridor length.
Less pantoscopic tilt leads to small improvement.
Usually SH is too low or they need a stronger add power. If it has been several patients.... could definitely be a SH issue.
I would look into a camber style freeform lens. The blank is by Younger, but you can put virtually any free-form back surface into it. The variable BC throughout will help eliminate the issue. Because you looking at... probably a 71 mm 5.25 BC lens blank back surfaced with 1.49-1.87 BD prism thinning... that leaves you with the 5 base at the top Rx which is great for the distance, but not for a +5.00 sph lens. If not available, change the panto to about 8-10 degrees and adjust the pads so that the lenses sit slightly higher.
Are you fitting pupil center? I use a penlight to make the corneal reflex.
10 to 1 its a problem with the digital fitting device I'm assuming you are using.
Try double checking your segs on these patients against whatever device it is.
Some Progressive Addition Lens designs use corridor lengths that are longer for hyperopes, shorter for myopes, due to effects from magnification/minification and prism. If the lens design in question does not have this optimization, minus powers might have too long of a corridor for comfortable near vision. But the opposite is happening here, that is, myopes aren't complaining, and that makes me think that that the software is overcorrecting the corridor length- too short for minus, too long for plus, with a possible too low of a fitting cross position aggravating the situation for hyperopes. If true, you could shorten the corridor 1mm to 2mm, if the software has that capability, although the preferred solution would be to use a better designed PAL.Originally Posted by george dimitrov
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.
We put our patients in the Shamir Autograph III fixed 15, when they experience having to lift glasses up for best reading clarity. We have found the ADD is pushed in sooner so they have more room to read and can use more natural posture. The fixed 18 has a good amount of reading area too, but wider corridor for those patients that do a lot of outdoor activities.
To add to this are you measuring from the deepest part of the frame following the boxing method, to pupil height? if not then for sure a SH issue.
Check Base Curve. If they moved from a traditional progressive to a freeform progressive, they may be in a significantly flatter base curve, so their perception is that they do not have enough magnification. This is a phenomenon that goes away with time, usually, but otherwise, you may need to change base curve. In the sample Rx given, I would think the problem would go away within the week, assuming proper fit.
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