Depending on the equipment used by the doctor, a prescription may be in plus or minus cylinder form. For surfacing, the lab uses the minus form, meaning if a prescription is written in a plus cylinder form it must be transposed before processing.
Transpose a prescription written in plus cylinder form to minus cylinder form as follows:
1. Add the sphere and cylinder powers to determine the new sphere power.
2. Change the sign of the cylinder.
3. Change the axis by 90 degrees.
Example:
Transpose -3.00 +2.00 x 30
1. Add the sphere and cylinder powers to determine the new sphere power.
(-3.00) + (+2.00) = -1.00
2. Change the sign of the cylinder
-2.00
3. Change the axis by 90 degrees.
120
The transposed prescription is:
-1.00 -2.00 x 120
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This programme is is helping me so much. Thanks
Perfect … Thx alot … It’s been long time which am
Practicing but suddenly have confused all transposition I would like to read once about cross Cylinder as well .
Thx
Thank you. It was really clear and well explained.
What if the sphere is plano. For example
Plano-1.00X005 ? Is the sphere plano or -1.00?
-1.00+1.00×95
Comment – sir-1 cyl 90′ ka transposition kya hoga