Erick E. Mena-Linares, Department of microsurgery anterior eye segment, Hospital General de México, Mexico City, Mexico José R. Ponce-Martínez, Department of microsurgery anterior eye segment, Hospital General de México, Mexico City, Mexico Olga M. Messina-Baas, Department of microsurgery anterior eye segment, Hospital General de México, Mexico City, Mexico María F. Loya-Carrera, Department of microsurgery anterior eye segment, Hospital General de México, Mexico City, Mexico


Introduction: The challenge of calculating intraocular lens (IOL) power after refractive surgery such as radial keratotomy (RK) remains unresolved after two decades. At present, there is an increase in patients with this history. Objectives: The objectives of the study were to determine the difference in refractive error after surgery between the Barrett True-K No History and Panacea formulas, for the calculation of IOL in cataract operated patients with a history of RK. Materials and methods: An observational, analytical, cross-sectional, and retrospective study was conducted. The power of the IOL was calculated, with the Barrett True-K No History and Panacea formulas, and the IOLMaster 500 biometer. Two groups were studied. The predicted spherical equivalent was adjusted to obtain the power of the final implanted lens. The result of the predicted spherical equivalent was subtracted from the actual spherical equivalent, thus the refractive error was obtained for each formula. Student’s t-test was used for independent groups. Results: The error with the Barrett True-K No History formula was −0.16 ± 1.12, whereas the error with the Panacea formula was −0.93 ± 1.22. p = 0.346. Conclusion: There was no statistically significant difference when comparing these two formulas, which showed that Panacea is as effective as Barrett True-K No History in cataract-operated patients with a history of RK.



Keywords: Formulas. Barrett True-K No History. Panacea. Biometrics. Radial keratotomy.