Accuracy of Toric Intraocular Lens Formulas in Eyes With Previous Myopic Laser Vision Correction

To compare the refractive prediction accuracy of two modern toric intraocular lens power formulas, using predicted or measured posterior corneal astigmatism, in eyes with a history of previous myopic laser vision correction (LVC).

This retrospective case series included 182 eyes with a history of previous myopic LVC that underwent uncomplicated cataract surgery with implantation of a monofocal non-toric IOL. Preoperative biometry was performed with swept-source optical coherence tomography. Spherical equivalent and refractive astigmatism prediction accuracy of the Barrett True K Toric and Emmetropia Verifying Optical (EVO) Toric formulas, using predicted posterior corneal astigmatism (PPCA) or measured posterior corneal astigmatism (MPCA), was analyzed using vector analysis and the Eyetemis online tool (https://eyetemis.com/).

For spherical equivalent prediction accuracy, the EVO Toric formula with MPCA had the highest proportion of eyes within ±0.50 diopters (D) (68%) and the lowest mean absolute error (0.419 D). The trimmed mean spherical equivalent prediction error for Barrett True K MPCA was significantly smaller than for Barrett True K PPCA (P < .01). With respect to refractive astigmatism, there was no significant difference in the absolute refractive astigmatism prediction error for EVO PPCA compared to EVO MPCA (P = .89). However, the refractive astigmatism prediction error for Barrett PPCA was smaller than for Barrett MPCA (P < .01).

Measured posterior corneal astigmatism improves the prediction accuracy of both the EVO and Barrett True K toric formulas with respect to the spherical equivalent but has a detrimental effect on the refractive astigmatism prediction accuracy of the Barrett True K toric formula.