New regression formula for toric intraocular lens calculations

Abulafia, Adi; Koch, Douglas D.; Wang, Li; Hill, Warren; Assia, Ehud I.; Franchina, Maria; Barrett, Graham D.

doi:10.1016/j.jcrs.2016.02.038

Cited by 93 publications

(86 citation statements)

References 30 publications

(52 reference statements)

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“…The present study has several strengths, which include a relatively large sample size (109 versus 61, 19 62, 20 and 46 21 ) compared to many published works in this domain. It also includes only one eye from each subject (avoiding paired organ biases) and is also the first study to report upon performance of the EVO Toric Formula v2.0 on an IOL platform other than the Acrysof IQ (Alcon, Fort Worth, TX).…”

Section: Discussionmentioning

confidence: 98%

“…Note that the RA prediction error vector in the present study is consistent with previously published work from Abulafia et al (0.55 @ 180) on similar legacy calculators. 8 , 19 The higher RA prediction error vector magnitude and ATR orientation associated with these legacy calculators stem from the now well-established contribution of the posterior cornea. The posterior cornea is known to have its steep axis of curvature oriented vertically in 85–90% of cases, resulting in an optical contribution of ≈ 0.3 D oriented horizontally.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

<p>Predictability of Residual Postoperative Astigmatism After Implantation of a Toric Intraocular Lens Using Two Different Calculators</p>

Pantanelli

Kansara

Smits

2020

OPTH

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Purpose To compare predictability of postoperative refractive astigmatism (RA) using the Emmetropic Verifying Optical (EVO) Toric Formula v2.0 to one that accounts only for anterior corneal astigmatism. Methods This is a secondary analysis of de-identified data from a clinical trial including 9 sites across the United States. Preoperative biometry was used to predict postoperative RA with the implanted toric IOL using legacy enVista and EVO online calculators. The RA prediction error was computed between back-calculated postoperative RA and predicted residual RA. Outcome measures included vector (centroid) and arithmetic mean RA prediction error. Results Comparison of calculators was based on 109 eyes, 97 (89%) of which were implanted with a toric IOL with an effective astigmatism power of 1.4 D or less. Centroid of the RA prediction errors was 0.37 D @ 178 and 0.17 D @ 090 for the legacy and EVO calculators, respectively (p < 0.0001). The proportion of eyes with an absolute RA prediction error ≤0.5 was 47.3% and 49.1% (p = 0.78), while the proportion of eyes ≤1.0 D was 82.7% and 89.1% (p = 0.03). Differences in the proportions ≤0.5 D existed for WTR (p = 0.015) but not ATR (p = 0.75) eyes. The proportion in which orientation of the predicted RA (ATR, WTR, or oblique) matched the actual RA was 62% and 78% for legacy and EVO calculators, respectively (p = 0.0029). Conclusion The EVO Toric Formula v2.0 out-performed the legacy calculator with regards to predictions in eyes with low astigmatism.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

<p>Predictability of Residual Postoperative Astigmatism After Implantation of a Toric Intraocular Lens Using Two Different Calculators</p>

Pantanelli

Kansara

Smits

2020

OPTH

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“…By using the Barrett calculator, the predicted postoperative refraction was closer to target refraction for the spherical equivalent, sphere, and astigmatism than by using a standard calculator. By adjusting the standard calculators with new nomograms considering the TCA of the cornea, the error of prediction can be reduced to similar values to those that the Barrett calculator delivers [ 11 ].…”

Section: Discussionmentioning

confidence: 99%

“…The lowest predicted residual astigmatism has been reached by using the Barrett toric calculator [ 10 ]. Adjustment of standard industry-based calculators by a new regression formula to calculate the TCA can improve the error in predicted postoperative astigmatism [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Comparison of Two Toric IOL Calculation Methods

Kern

Kortüm

Müller

et al. 2018

Journal of Ophthalmology

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Purpose To compare two calculators for toric intraocular lens (IOL) calculation and to evaluate the prediction of refractive outcome. Methods Sixty-four eyes of forty-five patients underwent cataract surgery followed by implantation of a toric intraocular lens (Zeiss Torbi 709 M) calculated by a standard industry calculator using front keratometry values. Prediction error, median absolute error, and refractive astigmatism error were evaluated for the standard calculator. The predicted postoperative refraction and toric lens power values were evaluated and compared after postoperative recalculation using the Barrett calculator. Results We observed a significant undercorrection in the spherical equivalent (0.19 D) by using a standard calculator (p ≤ 0.05). According to the Baylor nomogram and the refractive influence of posterior corneal astigmatism (PCA), undercorrection of the cylinder was lower for patients with WTR astigmatism, because of the tendency of overcorrection. An advantage of less residual postoperative SE, sphere, and cylinder for the Barrett calculator was observed when retrospectively comparing the calculated predicted postoperative refraction between calculators (p ≤ 0.01). Conclusion Consideration of only corneal front keratometric values for toric lens calculation may lead to postoperative undercorrection of astigmatism. The prediction of postoperative refractive outcome can be improved by using appropriate methods of adjustment in order to take PCA into account.

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“…Toric intraocular lens calculation is based on measurements of the anterior surface of the cornea. More recently, estimation algorithms have been introduced for the posterior surface of the cornea, depending on the steep axis of the astigmatism on the anterior surface of the cornea [27][28][29][30]. These estimations have resulted in significant improvements in toric IOL power calculations, compared with conventional ones that do not include measurements of the posterior cornea [31].…”

Section: Ss-oct and Cataract Evaluationmentioning

confidence: 99%