Eye Pro:

Toric IOL Misalignment Calculator


This program estimates the Power, Orientation, Misalignment and Rotation of a Toric IOL implanted in the eye starting from a known Pre- and Post-operative Astigmatism expressed either in positive or negative cylinder notation.

When entering data, either Refractions (Es: -4.50 for Magnitude; 180 for Axis) or Corneal measurements (Es: 4.50 for Magnitude; 90 for Meridian) can be used.

A Toric lens is considered to be aligned when its marks are aligned along the pre-operative steep corneal meridian (or 90 degrees away from the negative cylinder axis in case of refractions). This is assuming that the Toric IOL marks indicate the positive cylinder axis.


  1. t-IOL Orientation: this is the estimated Axis of the Toric IOL (i.e. the marks location).

  2. t-IOL Misalignment: Negative values indicate an Anti-Clock-Wise (ACW); Positive values indicate a Clock-Wise (CW) rotation in reference to the perfect alignment.

Note: the estimated Toric IOL Cyl Power is calculated at the same plane in which the inputs are entered (i.e. either at the corneal or spectacle plane).

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