Optimization of Toric IOL Calculation

Implantation of toric IOLs is a predictable method of treating corneal astigmatism and results in good visual and refractive outcomes. The ideal toric IOL candidate has regular and symmetric astigmatism, but patients with mild, stable irregular astigmatism may also benefit. Ignoring the effect of the posterior corneal astigmatism on the total corneal astigmatism leads to astigmatism prediction errors when implanting toric IOLs. It is preferable to leave patients with a slight amount of with-the-rule astigmatism to compensate for the against-the-rule shift that occurs with advancing age. The most important complication of toric IOLs is misalignment of the IOL, which can occur due to (1) inaccurate calculation of the ideal IOL alignment, (2) inaccurate alignment of the IOL during surgery, or (3) postoperative rotation of the IOL.