Analysis of accuracy of twelve intraocular lens power calculation formulas for eyes with axial hyperopia

The purpose was to compare twelve intraocular lens power calculation formulas for eyes smaller than 22.0 mm in terms of absolute error (AE), the percentage of postoperative emmetropia, and agreement interval in Bland-Altman analysis.

The data of hyperopic patients who underwent uneventful phacoemulsification between January 2016 and July 2021 were reviewed. Intraocular lens power was calculated using Holladay 1, SRK/T, Hoffer Q, Holladay 2, Haigis, Barrett Universal II, Hill-RBF, Ladas, Kane, Emmetropia Verifying Optical (EVO), Pearl-DGS, and K6 formulas. Three months after phacoemulsification, refraction was measured, and the mean AE was calculated. The percentage of patients with full visual acuity (VA) without any correction, with ± 0.25D, ±0.5D, ±0.75D, and limits of agreement for each formula was established.

Seventy-two patients, whose ocular axial length (AL) ranged between 20.02 mm and 21.98 mm, were included. The Kane formula achieved the lowest mean AE of 0.09 ± 0.09 just before EVO (0.12 ± 0.09), Hill-RBF (0.17 ± 0.12), and Hoffer Q formulas (0.19 ± 0.16). In addition, with the Kane formula, the percentage of patients with full VA without any correction (80.6%) was the highest ahead of EVO and Hoffer Q formulas (51.5% and 50.0%, respectively). Finally, Kane, EVO, and Hill-RBF obtained the lowest agreement interval (0.4923, 0.5815, and 0.7740, respectively).

The Kane formula is recommended for intraocular lens power calculation for eyeballs with the AL smaller than 22.0 mm. The EVO formula gives very promising results in regarding the accuracy of intraocular lens power for hyperopic eyes.