Accuracy of Intraocular Lens Power Calculation Formula

Aim: To investigate the accuracy of seven currently-used intraocular lens (IOL) power calculation formulae. Patients and methods: A total of 429 eyes of 429 patients were retrospectively analyzed. A low-optical coherence reflectometry device (Lenstar, Haag-Streit) was used for the calculations. SRK/T, Hoffer Q, Haigis, Holladay-2, Olsen, Hill-RBF and Barrett Universal II formulae were studied. The study included patients who underwent phacoemulsification surgery with a 2.8 mm corneal cut by a single surgeon. Refraction measurement was done at the first postoperative visit, and then spherical equivalent values were recorded for each patient. Mean absolute error (MAE) was calculated as the absolute value of postoperative spherical equivalent value minus predicted error for each formula. Results: The mean age of the patients was 67.51 ± 5.75 years. Mean axial length was 23.42 ± 2.02 mm (min: 20.03, max: 32.68, median: 23.09). Mean IOL power was 21.1 ± 5 diopters (min: -1.5, max: 3.5). Postoperative spherical values were between -1.50 and +1.00 diopters. Mean absolute errors were 0.317 for SRK/T, 0.280 for Holladay-2, 0.273 for Hoffer Q, 0.264 for Haigis, 0.347 for Barrett Universal II, 0.339 for Hill-RBF, and 0.351 for Olsen. Conclusion: Hoffer Q, Holladay-2, and Haigis formulae had significantly lower MAE values than SRK/T, Barrett Universal II, Hill-RBF, and Olsen formulae. Although the Haigis formula gave the lowest MAE value, there was no significant difference with the Hoffer Q and Holladay-2 formulae.