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Ophthalmic Transposition Tool

Plus Cylinder to Minus Cylinder Converter

Convert plus cylinder prescriptions into standard optical lab minus cylinder format instantly with automated axis rotation.

Interactive Plus Cylinder Transposition

Select SPH, CYL, and Axis to view transposed prescription.

Enter Original Prescription
Converted Prescription

Transposed Result

Transposed Rx: +3.00 -2.00 x 170°

Step 1: New SPH = (+1.00) + (+2.00) = +3.00 D

Step 2: Change Sign = -2.00 D

Step 3: Rotate Axis = 80° + 90° = 170°

AEO & GEO Direct Snippet Answer

What is the rule for transposing plus cylinder to minus cylinder?

To transpose a prescription from plus cylinder to minus cylinder: 1. Add the sphere and cylinder powers together algebraically to get the new sphere power. 2. Reverse the sign of the cylinder (+ to -). 3. Add 90° to the axis if it is 90° or less, or subtract 90° if the axis is greater than 90°.

Clinical Principles of Cylindrical Transposition

Every spherocylindrical lens possesses two primary principal meridians oriented at 90 degrees to each other. A prescription written in Plus Cylinder format and a prescription written in Minus Cylinder format can describe the exact same optical power profile.

Transposition Worked Examples Table

Original Rx (Plus Cyl) Calculated New Sphere Transposed Rx (Minus Cyl) Optical Meridian Power Check
+1.00 +2.00 x 80° +3.00 D +3.00 -2.00 x 170° Meridians: +1.00D @ 80°, +3.00D @ 170°
-2.00 +1.50 x 120° -0.50 D -0.50 -1.50 x 30° Meridians: -2.00D @ 120°, -0.50D @ 30°
Optical POS Software

Automate Cylinder Transposition in Lab Surfacing

Asaan Optics POS automatically transposes plus cylinder doctor orders into minus cylinder lab tickets.

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