Alcon Toric Calculator
Calculate the recommended toric IOL power and alignment for cataract surgery using Alcon's formula.
Published by:
isCalculator Editorial Team
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How to use this tool?
How to Use the Alcon Toric Calculator
This calculator estimates the recommended toric IOL cylinder power and alignment axis based on corneal astigmatism, surgically induced astigmatism (SIA), and incision location. Follow these steps:
- Enter Keratometry (K1 & K2) – Input the two keratometry readings in diopters (D) separated by a slash, e.g.,
44.0/45.0. The first value is the flat meridian, the second is the steep meridian. - Set Steep Axis – Enter the steep axis of the cornea in degrees (0–180). This is the meridian of the higher K value.
- Provide Surgically Induced Astigmatism (SIA) – Enter the expected SIA in diopters (e.g., 0.5 D). This accounts for astigmatism change from the incision.
- Specify Incision Location – Enter the incision position in degrees (0–180). The calculator adjusts SIA based on the angle difference from the steep axis.
- Click "Calculate" – The tool validates inputs and displays:
- Cylinder Power – Recommended toric IOL cylinder (rounded to nearest 0.25 D).
- Axis – Alignment axis for the IOL (same as steep axis).
- Residual Astigmatism – Expected remaining astigmatism after surgery.
All values must be in diopters (D) and degrees. Ensure keratometry is in the correct format (e.g., 44.0/45.0). The calculator uses a simple trigonometric model to adjust SIA based on incision angle.
Previous Results
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Frequently Asked Questions
It is a tool that calculates the recommended toric IOL cylinder power and axis based on preoperative keratometry, steep axis, surgically induced astigmatism, and incision location.
The cylinder power is rounded to the nearest 0.25 diopter, which is typical for toric IOLs.
Residual astigmatism is the amount of astigmatism remaining after the toric IOL implantation, calculated as the difference between the corneal astigmatism and the combined effect of the IOL cylinder and SIA.
