Accuracy of Intraocular Lens Calculations Using the IOLMaster in Eyes with Long Axial Length and a Comparison of Various Formulas

Purpose: To evaluate the relationship between eyes with long axial length (AL) and postoperative refractive errors as predicted by various commonly used intraocular lens (IOL) formulas using the Zeiss IOLMaster (Carl Zeiss Meditec, Jena, Germany). Design: Retrospective chart review. Participants: A total of 53 eyes of 36 patients with an AL of more than 27 mm who underwent uncomplicated cataract extraction with IOL implantation. Methods: Data were obtained from patient charts and the IOLMaster. Main Outcome Measures: The main parameters assessed were AL, preoperative best-corrected visual acuity (BCVA), postoperative BCVA, and mean absolute error (actual postoperative spherical equivalent minus predicted postoperative spherical equivalent). Mean absolute error was calculated using predicted spherical equivalents obtained from the Holladay 1, Holladay 2, SRK/T, Hoffer Q, and Haigis formulas. Results: The Haigis formula was found to be the most accurate in predicting postoperative refractive error in long eyes. The SRK/T formula was the second most accurate, followed by the Holladay 2, then the Holladay 1, then the Hoffer Q. All formulas predicted a more myopic outcome than was actually achieved. Conclusions: These results suggest using the Haigis, SRK/T, or Holladay 2 formulas for very long eyes. It is also advisable to aim for a more myopic result than is intended.