1. What is Rx Transposition?

Rx transposition is the process of converting a spectacle prescription from plus cylinder form to minus cylinder form, or vice versa. This calculator helps opticians and eye care professionals quickly transpose prescriptions.

2. How Does the Calculator Work?

The calculator uses the following transposition formula:

Where:

• New Sphere = Old Sphere + Old Cylinder
• New Cylinder = -Old Cylinder
• New Axis = Old Axis ± 90° (whichever keeps it between 1-180°)

Explanation: The transposition changes the form of the prescription without altering its optical effect.

3. Importance of Rx Transposition

Details: Proper transposition is essential for accurate lens manufacturing, prescription verification, and communication between eye care professionals.

4. Using the Calculator

Tips: Enter the sphere, cylinder, and axis values from the original prescription. The calculator will automatically compute the transposed values.

5. Frequently Asked Questions (FAQ)

Q1: Why transpose a prescription?
A: Different manufacturers may use different forms (plus or minus cylinder), so transposition ensures the correct lens is made.

Q2: Does transposition change the prescription's effect?
A: No, it's just a different mathematical representation of the same optical correction.

Q3: How do I handle prescriptions with no cylinder?
A: If cylinder is 0, the prescription is already in both forms and doesn't need transposition.

Q4: What about axis values?
A: The axis is always perpendicular (90° different) in the transposed form, staying between 1-180°.

Q5: Can I use this for contact lens prescriptions?
A: While the optical principles are the same, contact lens prescriptions often require additional parameters.