In optometry and ophthalmology, there are two main notations used to describe eyeglass or contact lens prescriptions: “Plus Cylinder Form” and “Minus Cylinder Form.” Depending on the preference of the doctor or the requirements of a particular lens manufacturer, one might need to transpose, or switch, between these two notations.
The process of transposing involves adjusting the sphere, cylinder, and axis values in a specific manner:
New Sphere = Old Sphere + Old Cylinder
New Cylinder = – Old Cylinder
New Axis = Old Axis + 90° (If the result is 180° or more, subtract 180°.)
Different eyewear labs or lens manufacturers may require prescriptions in a particular notation. Transposing ensures that the correct lens power is produced, regardless of the notation used.
How to Use Transpose Rx Calculator:
- Input the original sphere, cylinder, and axis values into the fields provided.
- Click the “Transpose” button.
- Review the transposed prescription in the “Transposed Prescription” section.
Note: The values generated by this tool are based on standard transposition methods. Always consult with an optometrist or ophthalmologist to ensure prescription accuracy.