EyeWorld Asia-Pacific September 2019 Issue

54 EWAP SEPTEMBER 2019 Vergence Ray tracing #TVKƂEKCN KPVGNNKIGPEG Combination Holladay 1 Hoffer Q SRK/T Haigis Barrett Universal II Holladay 2 Olsen Phaco Optics Okulix Hill-RBF Clarke Ladas Super Formula FullMonte IOL +1. ECNEWNCVKQP HQTOWNCU (WPEVKQPCN ENCUUKƂECVKQP Source: Mitchell Weikert, MD REFRACTIVE Is it time to change how we talk about IOL calculation formulas? by Liz Hillman EyeWorld Senior Staff Writer Contact information Koch: dkoch@bcm.edu Weikert: mweikert@bcm.edu This article originally appeared in the May 2019 issue of EyeWorld . It has been UNKIJVN[ OQFKƂGF CPF CRRGCTU JGTG YKVJ permission from the ASCRS Ophthalmic Services Corp. F irst, second, third, and fourth generation: Most cataract surgeons are familiar with describing IOL power calculation formulas in such terms. But this is something that Douglas Koch, MD, Mitchell Weikert, MD, and œÌ…iÀà Ã>Þ Ì…i wi` ŜՏ` }iÌ away from, favoring instead a ÀiV>ÃÈwV>̈œ˜ œv ̅i vœÀ“Տ>à based on how they work. ˆ˜ ̅i wi`…>` œvÌi˜ Ì>Ži` about IOL calculation formulas in terms of function, the common lingo defaulted to generations. One reason to move away from this, Dr. Koch and Dr. Weikert explained, is because some people may assume that later generations are better than earlier ones, which isn’t necessarily the case. Dr. Weikert also said that as the formulas question his use of a third- generation formula (the Holladay 1). Dr. Koch, in its defense, said, “it’s a two-variable vergence formula that happens to be so good I still use it.” “Also to Dr. Weikert’s point, if we understand the mechanism, then we are better able to tailor our formula choice for any given patient,” Dr. Koch said. Dr. Koch said he thinks that /…i «Àœ«œÃi` ÀiV>ÃÈwV>̈œ˜ divides the formulas into the following categories: vergence, >À̈wVˆ> ˆ˜Ìiˆ}i˜Vi] À>Þ ÌÀ>Vˆ˜}] and combination. "ÛiÀ>] ÃÕV…> ÀiV>ÃÈwV>̈œ˜ “will help us communicate better,” Dr. Weikert said. Dr. Koch said that he and colleagues Li Wang, MD, Warren ˆ] ] >˜` Ƃ`ˆ ƂLՏ>w>] ] recommended reclassifying formulas based on their mechanism—and abandoning the “generation” terminology— ˆ˜ ̅i wÀÃÌ œv > Óä£Ç vœÕÀ‡«>ÀÌ editorial series in the Journal of Cataract & Refractive Surgery. 1 In the past, he said, while experts >Ài LՈÌ Õ«œ˜ >˜` Àiw˜i`] ̅i generation lingo starts to break down. Talking about the formulas based on how they work gives surgeons a better understanding of the limits and the assumptions that go into them. If you know how the formulas are derived and how they come about, it can help formulate your decision making. It can also help people make connections when they understand the common etiology, Dr. Weikert said. Dr. Koch said he uses the Holladay 1, Barrett, Hill-RBF, and Olsen. If using the “generations” V>ÃÈwV>̈œ˜] ܓi “ˆ}…Ì ̅i ňvÌ ˆ˜ V>ÃÈwV>̈œ˜ ܜՏ` be adopted more quickly if the editors of medical journals started requiring authors to refer to IOL calculation formulas based on their mechanism instead of generations. EWAP Editors’ note: Dr. Koch is Professor CPF #NNGP /QUDCEJGT CPF .CY %JCKT KP 1RJVJCNOQNQI[ $C[NQT %QNNGIG QH /GFKEKPG *QWUVQP CPF JCU ƂPCPEKCN KPVGTGUVU KP #NEQP CPF Carl Zeiss Meditec. Dr. Weikert is CUUQEKCVG RTQHGUUQT &GRCTVOGPV QH 1RJVJCNOQNQI[ $C[NQT %QNNGIG QH /GFKEKPG CPF JCU PQ TGNGXCPV ƂPCPEKCN interests. Reference 1. Koch DD, et al. Pursuing perfection in intraocular lens calculations: I. Logical approach for classifying IOL calculation formulas. J Cataract Refract Surg . 2017;43:717–718.