1. What is Prescription Transposition?

Prescription transposition converts between plus and minus cylinder forms of glasses prescriptions. This is important when comparing prescriptions or converting between different optical formats.

2. How Does the Calculator Work?

The calculator uses the following formulas:

Where:

• SPH — Sphere power (diopters)
• CYL — Cylinder power (diopters)
• Axis — Cylinder axis (0-180 degrees)

Explanation: The transposition changes the form of the prescription while maintaining the same optical correction.

3. Importance of Prescription Transposition

Details: Understanding prescription transposition is crucial for opticians, optometrists, and patients when comparing prescriptions or converting between different optical formats.

4. Using the Calculator

Tips: Enter the original sphere, cylinder, and axis values. The calculator will provide the transposed values in the opposite cylinder form.

5. Frequently Asked Questions (FAQ)

Q1: Why transpose a prescription?
A: Different optical labs may use different formats, and transposition allows comparison between plus and minus cylinder forms.

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

Q3: How precise are the calculations?
A: Results are rounded to the nearest 0.25 diopter, which is standard in optical prescriptions.

Q4: Can I transpose a prescription without cylinder?
A: If there's no cylinder (CYL = 0), the prescription remains the same after transposition.

Q5: Why does the axis change by 90 degrees?
A: The axis shift maintains the orientation of the cylinder correction when changing between plus and minus forms.