Dissimilar Heights
08-2008
If you measured R 18.5mm and L 16.5mm as shown in the picture below, how high are the fitting heights ordered?
Always order the heights as measured (even if only 0.5mm different).
If the progressive were a short corridor lens for a very small “B” measurement frame, the corridor may be 9 or 10mm long. In a 2.00 add, the power is changing 0.2D per mm so a lens that is fitted 2mm incorrectly will potentially be 0.4D off in power as the eyes rotate down to read.
So today, always order lenses at dissimilar heights if that is what was measured.
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