Rx Transpose

Convert between minus-cylinder and plus-cylinder notation. Axis normalised to 0–180°.

Professional Clinical Support

Prescription

Original

+2.00 −1.00 × 180°

Transposed

+1.00 +1.00 × 90°

Both cylinder forms

Minus cylinder

+2.00 −1.00 × 180°

Plus cylinder

+1.00 +1.00 × 90°

Calculation

  1. 01Input: +2.00 −1.00 × 180°
  2. 02Sphere: +2.00 + (−1.00) = +1.00
  3. 03Cylinder: −(−1.00) = +1.00
  4. 04Axis: 180° ± 90° → 90°
  5. 05Result: +1.00 +1.00 × 90°

Both forms describe the same sphero-cylindrical correction. Confirm the notation expected by the receiving system before ordering.

OS — Axis Convention Conversion

Left eye (OS) axis convention conversion only. The OD axis is not shown here and is never changed by this tool.

Axis Convention

OS Input

45°

TABO

OS Converted

135°

International

Calculated result only — OS axis convention conversion. The OD axis is unchanged. Confirm the axis and clinical decision independently.

Formula

  1. 01New Sphere = Sphere + Cylinder
  2. 02New Cylinder = −Cylinder
  3. 03New Axis = Axis ± 90° (normalised to 0–180°)

Clinical application

Transposition changes notation only — the refractive correction is identical. Use it when a lab, autorefractor or manufacturer expects a different cylinder convention.

OptiX Pro provides mathematical calculations, reference information, and fitting assistance. It does not replace professional clinical examination, manufacturer fitting guidelines, or professional judgement. Contact lens selection and prescription must be clinically verified.