Effect of pupil dilation on biometry measurements and intraocular lens power calculation formula with intraocular lens master 500

Purpose: The purpose was to study the effect of pupil dilation on biometric measurements and intraocular lens (IOL) power calculation using IOLMaster 500. Materials and Methods: A prospective observational study on 52 eyes of 52 cataract patients. The patients were examined with IOL Master 500 before and after pupil dilation. Axial length (AL), corneal power, anterior chamber depth (ACD), and the corresponding IOL power with Haigis and Sanders, Retzlaff, and Kraff (theoretical formula) (SRK/T) formula were compared. Results: There was no statistically significant difference in AL (+0.005 mm; P = .467) and corneal power (+0.001 D; P = .889) before and after dilation. The ACD increased significantly after dilation (+0.12 ±0.35 mm; P < 0.01). IOL power calculation based on SRK/T formula (−0.02 ±0.16, P = 0.20) was not affected, whereas a significant change in the calculation was found using the Haigis formula (+0.07 ±0.54, P = 0.03). Conclusion: There is no clinically significant effect of pupil dilation on the IOL Master 500 measurements of AL, corneal power, and IOL power calculated using the SRK/T formula. However, a significant increase in ACD and IOL power calculation is found using the Haigis Formula