Intraocular lens power calculation in challenging cases

Abstract

Abstract In this article, we reviewed recently published papers of intraocular lens (IOL) power calculation in special eyes. In short eyes, accurate estimation of effective lens position is critical, and the ZEISS artificial intelligence IOL calculator produces the best outcomes. In long eyes, accuracy has been improved with axial length (AL) adjusted formulas such as the Wang–Koch AL adjustment and newer IOL formulas. In keratoconic eyes, hyperopic refractive outcomes increase with steeper keratometric values, and accuracy is poor in eyes with keratometric values ≥50.0 D. Two keratoconus-specific formulas (Barrett True K for keratoconus and Kane keratoconus) have been introduced. In eyes undergoing combined Descemet membrane endothelial keratoplasty and cataract surgery, steeper corneas and corneas with a lower anterior/posterior ratio may have higher degrees of corneal flattening, and more myopia ranging from −0.75 to −1.0 D should be targeted. The postrefractive IOL power calculator from the American Society of Cataract and Refractive Surgery website has been a useful tool for postrefractive IOL power calculation. Recently, newer IOL formulas incorporating both anterior and posterior corneal measurements were introduced for eyes with previous corneal refractive surgery: Barrett True-K TK, Pearl-DGS, EVO 2.0, and Hoffer QST. It is recommended to obtain IOL calculations using as many formulas as possible and select the IOL power based on the consensus of multiple methods, with more weight given to the newer IOL power calculation formulas.