Toric Intraocular Lens Calculations in Eyes With Corneal Ectasia

PURPOSE: To analyze the accuracy of astigmatism correction in patients with corneal ectasia, using various toric intraocular (IOL) calculators. METHODS: Consecutive patients with corneal ectasia and a regular astigmatic component, who underwent cataract extraction with implantation of a toric IOL, were retrospectively reviewed. The predicted postoperative refractive astigmatism (RA) was calculated with the Barrett True K (BTK) toric calculator using predicted and measured posterior corneal astigmatism (PPCA and MPCA, respectively), both with and without the Integrated Keratometry (IK) tool. In addition, the Kane toric calculator was used, with its keratoconus function. Based on the manifest postoperative refraction, the error in the predicted astigmatism was calculated for each method. RESULTS: Compared in 36 eyes of 28 patients, IK-PPCA (0.09 diopters [D] @ 76) showed the lowest trimmed mean centroid prediction error for RA, followed by IK-MPCA (0.11 D @ 7), BTK-MPCA (0.12 D @ 55), Kane-Keratoconus (0.15 D @ 78) and BTK-PPCA (0.28 D @ 82). BTK-PPCA was the only method that significantly deviated from zero (P = .038), and significantly differed from BTK-MPCA (P = .013), IK-PPCA (P = .009), and IK-MPCA (P = .003). IK-MPCA led in precision and accuracy (trimmed mean 0.66 D and 0.67 D, respectively), but not significantly vs IK-PPCA (0.73 D, 0.74 D), BTK-MPCA (0.78 D, 0.79 D), Kane Keratoconus (0.80 D, 0.80 D), and BTK-PPC (0.84 D, 0.88 D). CONCLUSIONS: The use of multiple measurements, provided by the IK calculator, enhanced astigmatism correction with toric IOLs in eyes with corneal ectasia. The variability in ectatic corneas likely benefits from a multi-measurement approach.