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Prediction of residual astigmatism using intraoperative wavefront aberrometry vs a toric IOL calculator

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Session Details

Session Title: Toric IOL Calculations & Alignment

Session Date/Time: Sunday 23/09/2018 | 08:00-10:00

Paper Time: 08:46

Venue: Room A5

First Author: : M.Raimundo PORTUGAL

Co Author(s): :    J. Gil   A. Rosa   M. Quadrado   J. Murta           

Abstract Details


The Barrett Toric IOL calculator offers excellent performance by including posterior corneal astigmatism and effective lens position. We aimed to determine if Intraoperative Wavefront Aberrometry (IWA) can further improve residual astigmatism prediction compared to the recommended toric intraocular lens calculator.


Private Practice - Unidade de Oftalmologia de Coimbra (UOC), IDEALMED, Coimbra, Portugal.


Prospective study with eyes implanted with a toric IOL (SN6ATx, Alcon) using IWA (ORA, Alcon) for intraoperative toric power selection and residual astigmatism prediction. Residual astigmatism for the same toric IOL was back-simulated using the Alcon Barrett Toric calculator. The suggested toric power by the calculator was noted. Subjective refraction was obtained 3 months post-operatively. Astigmatism analysis was performed using the Alpins method. A difference vector was calculated for each prediction (IWA and calculator) by subtracting the predicted residual astigmatism from the observed post-operative astigmatism vector. Main outcome was the magnitude of the difference vector (median, MedAE; interquartile range, IQR).


Fifty eyes of 38 subjects were included. The chosen IOL cylindrical power using IWA differed from the chosen IOL cylindrical power using the Alcon Barrett calculator in 26/52 eyes (52%). We found no significant differences between eyes with matched and mismatched IOL cylindrical powers regarding preoperative biometric parameters (all p>0.05). While the overall MedAE was similar (MedAE IWA=0.49D, IQR IWA=0.36D vs MedAE Barrett=0.49D, IQR Barrett=0.58D; p=0.973), when there was a mismatch, MedAE was significantly lower using IWA (MedAE IWA=0.44D, IQR IWA=0.40D vs MedAE Barrett=0.73D, IQR Barrett=0.45D; p=0.028).


When there was a mismatch between the suggested toric power by IWA and the Barrett calculator (50% of cases), IWA had a lower median absolute residual astigmatism prediction error. Therefore, in this sample, IWA further enhanced toric refractive outcomes in a subset of eyes when compared to a recently introduced calculator that already accounts for posterior corneal astigmatism.

Financial Disclosure:

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

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