Analysis of vault prediction in phakic implantable phakic collamer lenses: manufacturer’s calculator vs theoretical formulae vs clinical practice

Abstract

Background: Implantable collamer phakic (ICL) intraocular lens sizing calculations are necessary to avoid complications associated to inadequate sizing. Historically, Holladay R, Dougherty, Hernández-Matamoros, and other authors have tried to create new formulas that solve calculation problems and provide higher reliability. In addition, in recent years, the appearance of new equipment, parameters, and formulas have led to significant progress. This paper compares the sizing according to manufacturer’s method and other methods. Methods: Forty-three eyes of 24 patients with EVO ICL implanted, with at least 1 year of follow-up, were analysed. The analysed variables were white to white (WTW), anterior chamber depth (ACD), ACW (angle-to-angle), crystalline lens rise (CLR), ICL size, vault measured at 1 week and 1 year after surgery, ICL size, and vault predicted by Nakamura-2 as well as vault size predicted by Igarashi. Results: Sizing calculation with Online Calculation and Ordering System according to WTW and ACD is a good indicator with 86% success rate. The calculation with Nakamura 2 suggests larger ICL sizes in 32.5% of cases and smaller in 18.6% of cases, while the resulting Vault according to Igarashi obtains better results without significant differences. Conclusions: ICL sizing according WTW and ACD, using the manufacturer’s algorithm, seems to be the most predictable method compared to other algorithms using other variables. The surgeon’s expertise also has a high importance in the final ICL size election.