Yonsei Med J.  2015 Jul;56(4):1097-1105. 10.3349/ymj.2015.56.4.1097.

Comparison of the Astigmatic Power of Toric Intraocular Lenses Using Three Toric Calculators

• Park HJ
• Lee H
• Woo YJ
• Kim EK
• Seo KY
• Kim HY
• Kim TI

• KMID: 2366353
• DOI: http://doi.org/10.3349/ymj.2015.56.4.1097

Abstract

PURPOSE
To compare the astigmatic power of toric intraocular lenses (IOLs) obtained from the AcrySof, TECNIS, and iTrace toric calculator in patients with preoperative with-the-rule (WTR) or against-the-rule (ATR) corneal astigmatism.
MATERIALS AND METHODS
Fifty eyes with cataract and corneal astigmatism greater than 0.75 diopters were enrolled in each group (WTR and ATR). Keratometric values were measured using autokeratometry, an IOLMaster, and an iTrace, which incorporated corneal topography and ray-tracing aberrometry. Based on measured keratometric values, the astigmatic power of each toric IOL was calculated using three toric calculators.
RESULTS
Bland-Altman plots showed good agreement between six pairwise corneal astigmatism values in both groups. The TECNIS calculator tended to suggest a higher astigmatic power of the toric IOL than the AcrySof calculator. With the higher astigmatism and keratometric values from the IOLMaster, in both groups, calculations from the AcrySof and TECNIS calculators resulted in higher calculated astigmatic powers than those from same calculators with autokeratometry-measured values, demonstrating good agreement. With the higher calculated astigmatic power values, the values from the iTrace toric calculator using keratometric values obtained from iTrace ray tracing wavefront aberrometry or iTrace simulated keratometry showed fair to moderate agreement with those from the other calculator-keratometry pairs in both groups.
CONCLUSION
To achieve the best refractive outcome after toric IOL implantation, understanding the differences in keratometric values between instruments and in calculated astigmatic power among toric calculator programs is necessary. Moreover, systemic analysis of each toric calculator in conjunction with postoperative data is required.

Keyword

Astigmatic power; toric IOL; toric calculator; corneal astigmatism; keratometry

MeSH Terms

Aberrometry
Aged
Aged, 80 and over
Astigmatism/physiopathology/surgery
*Cataract
Cornea/surgery
Corneal Topography
Eye
Female
Humans
*Lens Implantation, Intraocular
*Lenses, Intraocular
Male
Middle Aged
Phacoemulsification/*methods
Postoperative Period
Refraction, Ocular/*physiology
Visual Acuity/physiology

Figure

• 

  Fig. 1 Bland-Altman plots showing differences in corneal astigmatism between devices in WTR and ATR groups. The mean difference is represented by the horizontal solid line, and 95% limits of agreement are represented by dotted lines. (A) Autokeratometry vs. IOLMaster partial coherence interferometry. (B) Autokeratometry vs. iTrace ray tracing wavefront aberrometry. (C) Autokeratometry vs. iTrace simulated keratometry. (D) IOLMaster partial coherence interferometry vs. iTrace ray tracing wavefront aberrometry. (E) IOLMaster partial coherence interferometry vs. iTrace simulated keratometry. (F) iTrace ray tracing wavefront aberrometry vs. iTrace simulated keratometry. WTR, with-the-rule; ATR, against-the-rule.

• 

  Fig. 2 Agreement in calculated astigmatic power of toric intraocular lenses. Weighted kappa statistics values and corresponding 95% confidence intervals for agreement in calculated astigmatic power of toric intraocular lenses among 15 toric calculator-keratometry pairs in WTR and ATR groups are shown. AcrySof, AcrySof toric calculator; TECNIS, TECNIS toric calculator; iTrace, iTrace toric calculator; Auto, autokeratometry; IOLM, IOLMaster partial coherence interferometry; iTrace WF, iTrace ray tracing wavefront aberrometry; iTrace Sim, iTrace simulated keratometry.

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