Converting perscriptions from optician from plus to minus?!
Question: Converting perscriptions from optician from plus to minus!?
When the cyl part of a perscription is written as plus 0!.50 as opposed to minus 0!.50, how do I convert the axises of 132 and 90 back to how they would appear on my other perscriptions where the cyl is written as a minus!.
Thanks
Www@Answer-Health@Com
Thanks
Www@Answer-Health@Com
Answers:
The mathematical shortcut is:
1!. Combine the sphere and cylinder powers!. This is your new sphere power!.
2!. Change the sign of the cylinder power!.
3!. Add or Subtract 90 degrees from the axis!. This is your new axis!.
Cylinder power is referenced from the sphere power!. Axis indicates where the least cylinder power is located!.
To convert between plus and minus cylinder, you need to know the sphere power!. The easiest way is with an optical cross (writing out the actual powers in the two meridians and the degree measurements of where they occur)!. By drawing it all out, you're less likely to make a mistake with the math!.
+1!.00 +0!.50 x 090:
!.!.!.!.!.!.!.!.!.!.!.!.!.!.+1!.00!.!.!.!.!.!.!.!.!.!.!.!.!.!.!.!.
!.!.!.!.!.!.!.!.!.!.!.!.!.!.!.!.!.!.
1!. Combine the sphere and cylinder powers!. This is your new sphere power!.
2!. Change the sign of the cylinder power!.
3!. Add or Subtract 90 degrees from the axis!. This is your new axis!.
Cylinder power is referenced from the sphere power!. Axis indicates where the least cylinder power is located!.
To convert between plus and minus cylinder, you need to know the sphere power!. The easiest way is with an optical cross (writing out the actual powers in the two meridians and the degree measurements of where they occur)!. By drawing it all out, you're less likely to make a mistake with the math!.
+1!.00 +0!.50 x 090:
!.!.!.!.!.!.!.!.!.!.!.!.!.!.+1!.00!.!.!.!.!.!.!.!.!.!.!.!.!.!.!.!.
!.!.!.!.!.!.!.!.!.!.!.!.!.!.!.!.!.!.
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