Effectiveness, sensitivity and specificity of intraocular lens power calculation formulas for eyes of axial length smaller than 22.0 mm

Objective: To compare intraocular lens power calculation formulas’ for eyeballs shorter than 22.0 mm in terms of absolute error and receiver operating characteristic curves.
Material and methods: The data of hyperopic patients who underwent uneventful phacoemulsification with intraocular lens implantation in (…) between October 2015 and June 2019 were retrospectively reviewed. Intraocular lens power was calculated using Holladay1, SRK/T, Hoffer Q, Holladay2, Haigis, Barrett Universal II formulas. Power of implanted lens was based on Hoffer Q. Three months after phacoemulsification, refraction was measured and absolute error was calculated. Percentage of patients with full visual acuity without any correction and percentage of hyperopic patients for each formula was established. Receiver operating characteristic curves with cut-off point of axial length were drawn for each formula and area under the curve was evaluated.
Results: Fifty six patients (62 eyes) whose ocular axial length ranged between 20.58 mm and 21.97 mm were included in the study. Hoffer Q formula achieved the lowest mean absolute error of 0.09 (± 0.08 D), the highest (75.8%) percentage of patients with full visual acuity without any correction and the lowest (8.1%) percentage of postoperative hyperopia. Contrary, the SRK/T formula had the largest area under the curve (0.667).
Conclusions:
1. The Hoffer Q formula obtained the lowest level of absolute error in the study and seems to be recommended for intraocular lens power calculation for hyperopic eyes.
2. Receiver operating characteristic curves in assessment of intraocular lens power calculation formulas’ effectiveness need further studies