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Re: Kane et al.: A comparison of the accuracy of 6 modern toric intraocular lens formulas (Ophthalmology. 2020;127:1472-1486)

      I read the study conducted by Kane et al
      • Kane J.X.
      • Connell B.
      A comparison of the accuracy of six modern toric IOL formulas.
      comparing different toric intraocular lens (IOL) formulas. I noted a significant discrepancy between the actual postoperative cylinder percentages and the reported accuracy of the formulas. In Figure 1 (in the original article), the authors showed that about 78% of eyes were within 0.5 D cylinder after surgery. However, the most accurate formula reported in the study, the Kane formula, achieved a significantly lower 65.6%. This equates to a difference of 12.4% (102 eyes). It is understandable that actual clinical outcomes can be poorer than the predicted due to IOL rotation, variability in surgically induced astigmatism (SIA), or if the surgeon did not use a posterior corneal astigmatism formula. However, it is highly unusual for the actual clinical outcomes to be much better than the predicted, especially when postoperative keratometry and measured IOL axes are used in analysis. The only reasons I could think of are that (1) the formula used by the operating surgeon is far superior to that of any of the formulas compared, (2) the postoperative refraction was overly optimistic, or (3) there were inaccuracies in postoperative keratometry or IOL axis measurements. Could the authors indicate the formula used by the surgeon and explain this unusual discrepancy?
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      References

        • Kane J.X.
        • Connell B.
        A comparison of the accuracy of six modern toric IOL formulas.
        Ophthalmology. 2020; 127: 1472-1486
        • Melles R.B.
        • Kane J.X.
        • Olsen T.
        • et al.
        Update on intraocular lens calculation formulas.
        Ophthalmology. 2019; 126: 1334-1335

      Linked Article

      • A Comparison of the Accuracy of 6 Modern Toric Intraocular Lens Formulas
        OphthalmologyVol. 127Issue 11
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          To compare the accuracy of the Abulafia-Koch, the Barrett, the EVO 2.0, the new Holladay 2 with total surgical-induced astigmatism, the Kane, and the Næser-Savini toric intraocular lens (IOL) power formulas using a large database of toric IOL refractive outcomes.
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      • Reply
        OphthalmologyVol. 127Issue 12
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          We appreciate Dr Yeo’s interest in our article and thank him for his comments. We have provided additional commentary in the discussion below to provide clarification of any misunderstanding. We point Dr Yeo and interested readers to the outstanding editorial by Abulafia et al, 1 which provides the best exposition of the terminology and methodology required to conduct a valid toric intraocular lens (IOL) study. We are confident our methodology follows the protocol in that editorial.
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