Prediction of Refractive Outcome With Toric IOLs
To evaluate and compare the accuracy of different methods of measuring and predicting postoperative astigmatism with toric intraocular lens (IOL) implantation.
Postoperative corneal astigmatism was measured by 3 devices and compared to the manifest astigmatic refractive outcome in a series of patients with toric IOL. The error in the predicted residual astigmatism (PredRA) was calculated by vector analysis according to the measurement and calculation method used to predict the required toric IOL cylinder power.
The centroid errors in PredRA were ATR with the Alcon and Holladay toric calculators (0.53 to 0.56D). The centroid errors in PredRA were lower when applying the Baylor nomogram (0.21 to 0.26D) and were lowest for the Barrett toric calculator (0.01 to 0.16D),P<.001. The Barrett toric calculator had the lowest median absolute error (MedAE) in PredRA (0.35 to 0.54D, all devices) compared to the Alcon and Holladay toric calculators with or without the Baylor nomogram, P<.021. Using the Barrett toric calculator, the Lenstar-LS900 had a lower MedAE in PredRA (0.35D) than the IOLMaster-500 (0.42D, P=.152), the Atlas topographer SimK (0.54D, P<.001) and MeanK (0.48D, P=.008). The Barrett toric calculator and the Lenstar-LS900 achieved the most accurate results: 75% and 97.1% of eyes were within 0.50D and 0.75D of PredRA, respectively.
The prediction of the astigmatic outcome with toric IOLs can be improved with appropriate measuring devices and methods to establish the required toric IOL power.