Originally Posted by
Laurie
Hello 'Boarders,
Hope you are all enjoying your summer so far,
In regard to the thickness question for plus Attitudes, while I am not an expert in manufacture, a tidbit from a response to your question is below:
the PD which will also affect thickness. The 1.9 edge can be reduced depending on what the lab has set for the minimum edge thickness. A plus lens goes off of the minimum edge and that will vary by what the lab uses for the minimum depending on the frame type. Was this RX ordered with the frame trace or were box measurements used. If box measurements were used then the frame was calculated on a rectangle with 90 degree corners and we know that the odds of this being true or very slim.
The prism amount seems too many to be more than some of the other programs use but we have checked and rechecked these results. This particular RX with the amount of astigmatism and the angle of the astigmatism causes the prismatic amount to seem too much. Also since we use the total RX along with a more exacting frame wrap and pantoscopic tilt the prismatic amount is more not a generic prism amount.
also,
It is possible that generic programs on the market have small errors and also do not base their calculations on all parameters and are not based on an aspheric back and are only calculated using powers and not the actual effect of the compensated RX or the actual curves on the lens.
Hope this helps,
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