Hi everybody,
I need help with 2 matters pleaseeee!
1) I was just wondering if anyone remembers the formula for combining 2 sphero-cylinder lenses which their axises are not 90 to each other, for example:
+1.00 -2.00 x45
and
+2.00 -1.50 x90
2) why there is usually a prism mounted in most progressive (PAL) lenses.. ? I called the lab today and they said it's usually the outcome of grinding.. is there a better explanation for that?
Many Thanks everyone
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