Advancements in intraocular lens power calculation formulas

Purpose of review We review recent studies comparing intraocular lens (IOL) formulas with an emphasis on selection of the highest performing formulas based on patient axial length, age, and history of previous corneal refractive surgery. Recent findings The Barrett Universal II formula based on a theoretical model has consistently demonstrated high accuracy. The Olsen four-factor formula using ray tracing optics and the Hill-RBF calculator using artificial intelligence have also demonstrated good prediction results after being updated. Notably, the Kane formula, incorporating artificial intelligence, has overall shown the best performance for all axial lengths. Although newly developed and updated IOL formulas have improved refractive prediction in patients with short or long axial length eyes or prior history of corneal refractive surgery, these challenging cases still require special consideration. The Barrett True-K formula has shown accurate results regardless of preoperative data in eyes with previous myopic refractive surgery. Summary Advancements in optical biometry and IOL calculation formulas continue to improve refractive outcomes. The clinician can optimize refractive outcomes in the majority of patients with the use of formulas that have shown consistent results and accuracy in several large studies.