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  • Comparing Accuracy of Modern Toric IOL Formulas

    By Lynda Seminara
    Selected By: Stephen D. McLeod, MD
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    Journal Highlights

    Ophthalmology, November 2020

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    Kane and Connell compared the accura­cy of six toric IOL formulas and found that the Kane formula outperformed the others in predicting astigmatism outcomes following cataract surgery.

    This retrospective review included 823 patients (823 eyes) who underwent insertion of an Alcon SN6AT(2-9) IOL by the same surgeon during uncompli­cated cataract surgery. The six toric for­mulas evaluated were Abulafia-Koch, Barrett, EVO 2.0, Holladay 2 (with total surgical-induced astigmatism), Kane, and Naeser-Savini. The dataset used in the study was not part of the develop­ment of any of the formulas.

    Both pre- and postoperative biometry were measured with the IOL-Master 500 or 700. All calculations were performed using vector addition, and the predicted postoperative refrac­tive astigmatism was determined for each formula. The post-op refractive prediction error was calculated as the vector difference between the predicted and actual refractive astigmatism. Main outcome measures were the mean and standard deviation of the prediction error and the percentage of eyes with a prediction error within ±0.50 D.

    According to post-op keratometry and measurement of the IOL axis, the Kane formula had the highest pro­portion (65.6%) of eyes with predic­tion errors not exceeding ±0.50 D. The next-best performers were Barrett (59.9%) and Abulafia-Koch (59.5%). Compared with the five other formulas, the Kane formula had a significantly lower absolute prediction error (p < .001) and variance in prediction error (p < .01). The percentage of prediction errors did not differ substantially for the Barrett (59.9%), Abulafia-Koch (59.5%), and EVO 2.0 (58.9%) formulas.

    This research is one of the largest published comparative studies of toric formulas and is among the first to include three newer formulas (EVO 2.0, Holladay 2, and Kane). Although the Kane formula compared favorably to the others, the authors encourage further comparisons of these and other toric IOL formulas.

    The original article can be found here.