Transposing Prescriptions

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

9 Comments

  1. Ur programmes are educative,keep it up

  2. you are a good educator

  3. U really helped me. Thannks

  4. This programme is is helping me so much. Thanks

  5. 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

  6. Thank you. It was really clear and well explained.

  7. What if the sphere is plano. For example

    Plano-1.00X005 ? Is the sphere plano or -1.00?

    • -1.00+1.00×95

  8. Comment – sir-1 cyl 90′ ka transposition kya hoga

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