April 2014
Volume 55, Issue 13
ARVO Annual Meeting Abstract  |   April 2014
Comparison of measured corneal astigmatism and accuracy of intraocular lens power calculations using six different devices
Author Affiliations & Notes
  • Bruna Ventura
    Baylor College of Medicine, Houston, TX
    Altino Ventura Foundation, Recife, Brazil
  • Li Wang
    Baylor College of Medicine, Houston, TX
  • Sumitra Subramanyam
    Baylor College of Medicine, Houston, TX
  • Douglas D Koch
    Baylor College of Medicine, Houston, TX
  • Mitchell P Weikert
    Baylor College of Medicine, Houston, TX
  • Footnotes
    Commercial Relationships Bruna Ventura, None; Li Wang, Ziemer (C); Sumitra Subramanyam, None; Douglas Koch, Alcon (C), AMO (C), i-optics (C), Ziemer (C); Mitchell Weikert, Ziemer (C)
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 4848. doi:
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      Bruna Ventura, Li Wang, Sumitra Subramanyam, Douglas D Koch, Mitchell P Weikert; Comparison of measured corneal astigmatism and accuracy of intraocular lens power calculations using six different devices. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4848.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: In normal eyes undergoing cataract surgery, to compare corneal astigmatism measured by Optiwave Refractive Analysis (ORA; WaveTec Vision Systems, Inc.), IOL Master (Carl Zeiss Meditec), Lenstar LS900 (Haag-Streit AG), Atlas (Carl Zeiss), Galilei (Ziemer) and Cassini (i-Optics), and to assess the accuracy of intraocular lens (IOL) power calculation using the first three devices.

Methods: Prospectively, 17 normal eyes (preliminary data) undergoing cataract surgery were included. Using all devices except the ORA, three sets of preoperative corneal curvature measurements were obtained by a single observer. Three sets of intraoperative aphakic and pseudophakic measurements were obtained using the ORA. In addition, postoperative measurements were attained with Lenstar and Cassini. Analyzed parameters were astigmatism magnitude and axis, using vector analysis. The mean absolute prediction error (MAE) and the percentage of eyes with prediction errors within 0.50 and 1.00 diopters (D) were calculated for the ORA, IOL Master and Lenstar, using the Holladay 1 formula with the latter two devices. The prediction errors were determined by subtracting the 3-week postoperative refraction from the predicted refraction.

Results: Mean corneal astigmatism measured preoperatively was as follows: Lenstar 0.73 D at 97°, IOL master 0.68 D at 88°, Atlas 0.71 D at 95°, Galilei 0.70 D at 87°, and Cassini 0.58 at 76°. The mean expected residual astigmatism was 1.00 D at 100° by the aphakic ORA measurement and 0.84 D at 114° by the pseudophakic ORA measurement. Mean postoperative corneal astigmatism was 0.70 at 87° for the Lenstar and 0.65 at 81 for the Cassini. The MAEs were 0.13 D, 0.25 D, and 0.12 D for the ORA, IOL Master, and Lenstar, respectively, and there were no differences among devices (P > .05). In 91% of cases, ORA had a prediction error within ± 0.50 D, compared to 82% for IOL Master and 91% for Lenstar. All eyes (100%) were within 1.00 D of prediction error using the 3 devices.

Conclusions: The ORA tended to predict higher amounts of astigmatism. There were no differences in the accuracy of IOL power calculation among devices. More patients are being enrolled, and final results and conclusions will be presented.

Keywords: 465 clinical (human) or epidemiologic studies: systems/equipment/techniques • 428 astigmatism • 550 imaging/image analysis: clinical  

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