RESEARCH ARTICLE
Comparison of Four Intraocular Power Calculation Formulas in Keratoconus Eyes
Vicente J. Camps1, Ramy R. Fikry Riad2, Esteban Caravaca-Arens1, Fady E. Labib3, Veronica Mateo1, María T. Caballero1, David P. Piñero1, 4, *
Article Information
Identifiers and Pagination:
Year: 2021Volume: 15
First Page: 96
Last Page: 102
Publisher ID: TOOPHTJ-15-96
DOI: 10.2174/1874364102115010096
Article History:
Received Date: 17/10/2020Revision Received Date: 3/3/2021
Acceptance Date: 17/4/2021
Electronic publication date: 07/07/2021
Collection year: 2021
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
Introduction:
This study aimed to evaluate the differences in Intraocular Lens (IOL) power in keratoconus (KC) eyes between calculations obtained clinically with the most commonly used formulas in healthy eyes (SRK T, Holladay 1, Hoffer Q and Haigis) as well as to define predictive factors for such differences.
Methods:
This retrospective study comprised 43 keratoconus eyes of 22 patients with no previous ocular surgery. IOL powers were calculated with SRK T, Holladay 1, Hoffer Q, and Haigis formulas, considering the Effective Lens Position (ELP) of each formula and the desired refraction of 0 D (Rdes=0 D).
Results:
All differences between formulas were statistically significant and clinically relevant. Haigis formula always provided higher values compared to the rest of the formulas, with the highest differences observed when comparing Haigis with Hoffer (0.84 D) and Hoffer Q (1.17 D) formulas. The lowest difference was obtained for the comparison between SRK-T and Holladay 1 formulas (0.22 D). Differences of the Haigis formula compared to the rest were higher as the magnitude of the IOL power calculated decreased, becoming the patient more myopic. Increased differences between Haigis and Hoffer formulas were observed in eyes with deep anterior chambers, steeper anterior and posterior corneal surfaces, and high axial lengths.
Conclusion:
The most comparable results in IOL power in keratoconus are provided by the Holladay 1 and SRK T formulas, whereas the Haigis formula provides the most discrepant outcome. The consideration of the curvature of the second corneal surface in IOL power calculations in keratoconus may decrease the variability between calculation methods. However, other factors as anterior chamber depth or axial length are also relevant.
