Predictability of different calculators in the minimization of postoperative astigmatism after implantation of a toric intraocular lens
Received 23 April 2019
Accepted for publication 1 August 2019
Published 29 August 2019 Volume 2019:13 Pages 1649—1656
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Melinda Thomas
Peer reviewer comments 2
Editor who approved publication: Dr Scott Fraser
Filomena J Ribeiro,1,2 Tiago B Ferreira,1,3 Catarina Relha,1 Carina Esteves,1 Sylvia Gaspar1
1Ophthalmology Department, Luz Hospital, Lisbon, Portugal; 2Faculdade De Medicina Da Universidade De Lisboa, Lisbon, Portugal; 3NOVA Medical School, Lisbon, Portugal
Correspondence: Filomena J Ribeiro
Luz Hospital, Avenida Lusíada 100, Lisbon 1500-650, Portugal
Tel +351 21 710 4400
Purpose: To assess the efficacy of five calculators for toric intraocular lenses (IOL).
Methods: Retrospective comparative case series in cataract patients undergoing implantation of trifocal toric IOLs (PhysIOL FineVision POD FT). Inclusion criteria were age-related cataract and a corneal astigmatism between 0.90D and 4.50D. Refractive astigmatism predictability of five different toric calculators or calculation methods were compared. Furthermore, two groups were differentiated according to the type of astigmatism. The mean absolute error and the centroid errors in the predicted residual astigmatism from each calculator were evaluated.
Results: Fifty-one eyes of 43 patients were included in the study. For the standard toric calculator using anterior keratometry values only, the centroid prediction error was 0.39D±0.41@166º, which was reduced by the application of the PhysIOL toric calculator that includes the Abulafia-Koch regression formula and adjustment for the effective lens position (0.05D±0.34@167º), and also by the application of the Barrett toric calculator (0.07D±0.28@160º). Regarding the techniques that directly evaluate posterior corneal surface, the Holladay toric calculator, using total corneal power provided by a color-LED topographer, generated better results (0.10D±0.44@156º) than those using Scheimpflug camera data (0.23D±0.56@158º). Similar results were found for both types of astigmatism.
Conclusion: The PhysIOL and the Barrett toric calculators taking into account the posterior corneal astigmatism by mathematical models, yielded lower astigmatic prediction errors compared to a standard toric calculator based on anterior keratometry data only. When total corneal power measurements were used, prediction errors were lower with color-LED than with Scheimpflug based topography.
Keywords: astigmatism, toric IOL, toric IOL calculation
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