PhysIOL Toric Calculator
Estimate net corneal astigmatism after SIA, select the nearest PhysIOL toric model, and preview expected residual cylinder (including rotation effect).
What this calculator is for
A PhysIOL toric calculator helps you convert measured corneal astigmatism into a practical toric IOL choice. The key challenge is that astigmatism has both magnitude and axis, and surgery itself introduces additional astigmatic change (SIA). This tool uses vector math to combine those effects so you can estimate a more realistic toric target.
Inputs explained
Pre-op corneal astigmatism (D @ axis)
This is your baseline keratometric cylinder and steep axis from biometry/topography. The calculator treats it as the starting corneal vector.
Surgically induced astigmatism (SIA)
SIA reflects the effect of your incision strategy. Enter your personal or center-specific SIA magnitude and axis. Even small SIA values can shift the final toric requirement, especially in low-cylinder cases.
Corneal/IOL conversion factor
Toric cylinder printed on the IOL is not identical to cylinder at the corneal plane. This factor translates IOL-plane cylinder into corneal-plane effect. If you have manufacturer-specific constants or surgeon personalization, use those values.
Estimated rotation
Toric alignment matters. If the lens rotates off-axis, residual astigmatism increases quickly. This calculator lets you test how much cylinder might remain if post-op rotation occurs.
How the calculation works (short version)
- Convert corneal astigmatism and SIA into double-angle vectors.
- Subtract SIA vector from pre-op corneal vector to estimate net astigmatism to neutralize.
- Convert net target to required toric cylinder and axis at corneal plane.
- Map required cylinder to nearest available PhysIOL toric step.
- Apply rotation estimate and compute expected residual cylinder vector.
PhysIOL model map used in this page
The model list below is a simplified educational mapping used by this calculator to select the nearest lens step. Always verify with the latest manufacturer nomogram and lens platform documentation.
| Model | IOL Plane Cylinder (D) | Corneal Plane Example @ factor 0.69 (D) |
|---|---|---|
| PhysIOL Toric T1.00 | 1.00 | 0.69 |
| PhysIOL Toric T1.50 | 1.50 | 1.04 |
| PhysIOL Toric T2.00 | 2.00 | 1.38 |
| PhysIOL Toric T2.75 | 2.75 | 1.90 |
| PhysIOL Toric T3.50 | 3.50 | 2.42 |
| PhysIOL Toric T4.25 | 4.25 | 2.93 |
| PhysIOL Toric T5.00 | 5.00 | 3.45 |
| PhysIOL Toric T6.00 | 6.00 | 4.14 |
Practical use tips
- Use surgeon-personalized SIA whenever possible.
- Keep axis entry consistent with your keratometry convention.
- Re-check alignment marks and posterior corneal influence in your full workflow.
- If residual predictions are borderline, compare neighboring toric steps manually.
Important note
This page is intended for planning education and quick what-if analysis. It is not a substitute for a full clinical toric planning platform, posterior corneal modeling, or professional medical judgment.