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Toric IOL prediction accuracy using a novel regression formula

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Session Details

Session Title: Pseudophakic IOLs: Toric & Multifocal

Session Date/Time: Tuesday 08/09/2015 | 08:00-10:30

Paper Time: 08:06

Venue: Room 11

First Author: : A.Abulafia ISRAEL

Co Author(s): :    E. Assia   W. Hill   D. Koch   L. Wang   G. Barrett        

Abstract Details


To evaluate and compare the accuracy of 2 toric intraocular lens (IOL) calculators with or without a novel regression formula and to compare the results to the Barrett Toric Calculator.


Lions Eye Institute, Nedlands, WA, Australia, Ein-Tal Eye Center, Tel-Aviv, Israel.


A novel regression formula which was design to compensate for the posterior corneal astigmatism was derived using corneal measurement of 68 pseudophakic eyes. Corneal measurements taken by an IOLMaster device from a different center were processed by 2 toric IOL calculators with or without the application of the new regression formula and were compared to the Barrett Toric Calculator. The error in predicted residual astigmatism was calculated by subtracting the predicted residual astigmatism from the postoperative subjective refraction by vector analysis.


128 eyes were available for analysis. The centroid errors in predicted residual astigmatism were against-the-rule with the Alcon (0.56 diopters [D]) and Holladay (0.55 D) toric calculators and dropped down to 0.04D in both of the toric calculators when the regression formula was applied (P < 0.001). The Alcon and the Holladay Toric calculators had more accurate results with the regression formula: 93% and 92.2% of eyes were within 0.75 D of the predicted residual astigmatism as compared to 62.5% and 61.7% respectively, with no adjustments. The results of the Alcon and the Holladay Toric Calculator with the regression formula were similar to the results which were obtained by the Barrett Toric Calculator using no adjustments.


The prediction of the postoperative astigmatic outcome can be improved by using appropriate methods of adjustment for posterior corneal astigmatism.

Financial Interest:

One of the authors receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented

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