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Comparison of the astigmatic prediction error of a new toric intraocular lens calculator with other calculation methodologies

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Session Details

Session Title: Cataract
Session Date/Time: Saturday 10/02/2018 | 08:30-11:00
Paper Time: 09:42
Venue: Blue Hall

First Author: T.Ferreira PORTUGAL
Co Author(s): F. Ribeiro                 

Abstract Details


To compare the prediction error in residual astigmatism of a new toric calculator (PhysIOL Toric Calculator, PhysIOL SA, Liège, Belgium) incorporating the Abulafia-Koch formula with that of the Barrett Toric Calculator and of real total corneal astigmatism measurements obtained using a Scheimpflug camera (OCULUS Optikgeräte GmbH, Wetzlar, Germany) or a color-LED topographer (Cassini; i-Optics, The Hague, The Netherlands).


Hospital da Luz, Lisbon, Portugal.


In a retrospective case series of 51 eyes of 43 patients who underwent cataract surgery with toric IOL implantation (PhysIOL Finevision PODFT), predicted residual astigmatism by each calculation method was compared with manifest refractive astigmatism. Prediction error in residual astigmatism was calculated by vector analysis.


Both calculation methods that estimate total corneal astigmatism (new PhysIOL calculator and Barrett toric calculator) resulted in lower mean and centroid astigmatic prediction errors, and a larger number of eyes within 0.50 D of absolute prediction error than methods considering real measures (p < 0.001). For the new PhysIOL calculator centroid prediction error (CPE) was 0.05 ± 0.34 D @ 167º; for the Barrett toric calculator, CPE was 0.07 ± 0.28 D @ 160º (p = 0.758). For methods using real posterior corneal surface measurements, CPE was 0.23 ± 0.56 @ 158º D for the Scheimpflug camera and 0.10 ± 0.44 @ 156º D for the color-LED topographer (p = 0.003).


PhysIOL’s new calculator and the Barrett toric calculator yielded the lowest astigmatic prediction errors, with similar results between them. Of the methods that use real posterior surface measurements, the color-LED topographer resulted in a lower astigmatic prediction error.

Financial Disclosure:

, receives consulting fees, retainer, or contract payments from a competing company, , research is funded, fully or partially, by a company producing, developing or supplying the product or procedure presented

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