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Journal of Cataract & Refractive Surgery: October 2020 - Volume 46 - Issue 10 - p 1450-1451
doi: 10.1097/j.jcrs.0000000000000382
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Reply: Aghaei and Es'haghi mentioned that our method of assessing corneal astigmatism prior to toric IOL power and axis calculation was to repeat “both automated keratometry and IOLMaster (measurements) to achieve differences less than 0.50 diopter in power and 10 degrees in axis of astigmatism.” In fact, our method is more accurately described as it appears in our article thus: “For routine IOL calculation, the IOLMaster keratometric values obtained at the preoperative assessment were compared with similar data from the Nidek autokeratometer. Difference of more than 0.50 D in power or 10-degrees in axis between devices required repeated IOLMaster keratometry until an agreement between IOLMaster readings within these limits was reached.”1 Only IOLMaster measurements were repeated.

They asserted that “it would be more appropriate to consider the effect of possible corneal irregularities in astigmatic outcome in such patients because this discrepancy might have resulted from irregular corneal surface.” We, as stated in our article, excluded “eyes that had been subjected to keratorefractive procedures, had corneal disease, or other conditions reducing the visual potential.” Eyes with the irregularity referred to had already been excluded.

They mentioned that we “did not provide enough data about their eligibility criteria regarding corneal topographic measurements in this case series.” We would suggest that the above-mentioned exclusion criteria fully address this point.

We agree that caution must be exercised to recognize ectatic disorders and irregular corneas. Such eyes were not included in our dataset. We, however, do not agree that “it might not be reasonable to perform toric IOL implantation without assessing corneal topography” or that “Corneal topography is a prerequisite to obtain reliable measurements of astigmatism and axial position in candidates for toric IOL.” Clinical recognition of relevant corneal disease by history and clinical examination is possible in the hands of adequately trained ophthalmic surgeons. The necessity for routine tomographic or topographic examination of every case where a toric IOL is considered is not clearly established. Using the method we have described, we have published several unselected consecutive series demonstrating accurate clinical outcome in the absence of routine topographic measurement.2–4 Furthermore, the significant test-to-test variability in simulated keratometric measurement derived from one topographer vs the IOLMaster and an autokeratometer that we have demonstrated might make these values less, not more, suitable for toric IOL calculation in eyes with healthy corneas.5

Finally, we do not see in the reference quoted that topographic measurement is more likely to achieve optimal refractive outcome when there is a disagreement between optical biometry and automated keratometry in eyes with oblique astigmatism.6

The conclusion of that publication is, by contrast that, in reference to the 6 methods of keratometry examined that included autokeratometry and the IOLMaster, “Therefore, to maximize subsequent satisfaction of patients having toric IOL implantation in clinical practice, the use of any of these methods is necessary and sufficient for the comprehensive analysis of astigmatism.”—Shira Sheen Ophir, MD, Ben LaHood, FRANZCO, MBChB, Michael Goggin, FRCSI(Ophth), FRCOphth, FRANZCO, MS

REFERENCES

1. Sheen Ophir S, LaHood B, Goggin M. Refractive outcome of toric intraocular lens calculation in cases of oblique anterior corneal astigmatism. J Cataract Refract Surg 2020;46:688–693
2. Goggin M, Zamora-Alejo K, Esterman A, van Zyl L. Adjustment of anterior corneal astigmatism values to incorporate the likely effect of posterior corneal curvature for toric intraocular lens calculation. J Refract Surg 2015;31:98–102
3. Goggin M, van Zyl L, Caputo S, Esterman A. Outcome of adjustment for posterior corneal curvature in toric intraocular lens calculation and selection. J Cataract Refract Surg 2016;42:1441–1448
4. LaHood BR, Goggin M, Esterman A. Assessing the likely effect of posterior corneal curvature on toric IOL calculation for IOLs of 2.50 D or greater cylinder power. J Refract Surg 2017;33:730–734
5. Goggin M, Patel I, Billing K, Esterman A. Variation in surgically induced astigmatism estimation due to test-to-test variations in keratometry. J Cataract Refract Surg 2010;36:1792–1793
6. Lee H, Chung JL, Kim EK, Sgrignoli B, Kim TI. Univariate and bivariate polar value analysis of corneal astigmatism measurements obtained with 6 instruments. J Cataract Refract Surg 2012;38:1608–1615
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