Longitudinal Biometric Changes and Intraocular Lens Calculation Formula Accuracy in Delayed Cataract Surgery Cases

Purpose To compare postoperative refractive error (PE) calculated using intraocular lens (IOL) calculation formulas based on initial and remeasured ocular parameters in cases of delayed cataract surgery. Patients and Methods Patients who underwent delayed cataract surgery (ie, postponed for > 3 months) between February 2017 and April 2025 were included. Initial and remeasured ocular parameters were compared, namely axial length, mean keratometric power, anterior chamber depth (ACD), and lens thickness (LT). Expected refractions were calculated using the Sanders-Retzlaff-Kraff/Theoretical (SRK/T), Haigis, Barrett Universal II (BU II), Kane, and Emmetropia Verifying Optical (EVO) formulas. PEs were compared between the initial and remeasured data for each IOL calculation formula. Results The study included 57 eyes from 57 patients. Cataract surgery was delayed for an average of 14 months. Comparing the initial versus remeasured data, ACD deeper significantly and LT thinner significantly among the ocular parameters. The mean PE indicated a significant myopic shift for both the Haigis formula (0.02 D to −0.05 D) and EVO formula (0.00 D to −0.06 D) (paired t-test: p = 0.04, 0.03), while the other formulas had no significant differences. The mean absolute error and median absolute error showed no significant differences among the IOL calculation formulas. Based on the remeasured data, the results of the multiple regression analysis showed that only LT was a significant associated factor in the Haigis formula (estimate = 0.56, p = 0.02), whereas no significant associated factors were identified for the EVO formula. Conclusion It was suggested that the characteristics of each IOL calculation formula must be taken into consideration when selecting IOL power for delayed surgery.