Comparison of toric intraocular lens calculation using the new corneal curvature measurement methods and the haigis suite, barrett tk, barrett toric, and z calc formulas

Background: More than 50% of patients undergoing cataract surgery have corneal astigmatism ≥ 0.75 diopters (D). A fundamental factor for the calculation of the intraocular lens (IOL) is the power of corneal refraction, which can be calculated with different methods and incorporated into different mathematical prediction models. Little information has been written comparing new formulas that take into account posterior keratometry. Aims and Objectives: Compare the prediction of the ideal IOL with different formulas that use anterior keratometry and posterior keratometry measured by different devices. Setting: Private practice, Guadalajara, Jalisco, Mexico. Materials and Methods: A descriptive, observational and retrospective study was carried out where 50 healthy eyes with cataract and a degree of corneal astigmatism >1 D were evaluated, IOL calculation was compared using the anterior and total keratometries measured with the Zeiss IOL master 700 and the total corneal refractive power (TCRP) keratometries of the Oculus Pentacam. The results were also compared with the Haigis Suite, Barrett TK and Z Calc formulas. The IOL used for the analysis was the Zeiss AT TORBI 709M/MP. Results: It was found that the different formulas can generate different predictions in the cylinder power but no significant differences in the sphere power. Measurement of the posterior cornea did not significantly change the selection of the ideal IOL for implantation. Calculations with Haigis Suite and Z Calc are very similar. Barrett TK-Toric uses less cylindrical power than Haigis Suite and Z calc, regardless of the method chosen to measure corneal power. Conclusion: Our results contribute to clarify the current scenario where the great variety of options for the calculation of IOL generates uncertainty about which method generates better results of postoperative refraction.