April 2010
Volume 51, Issue 13
ARVO Annual Meeting Abstract  |   April 2010
Recentration to the Pupil Center Provides Consistency of Central Anterior Curvature Calculation Under Conditions of Misalignment
Author Affiliations & Notes
  • J. R. Lewis
    Ophthalmology, Biomed Engineering,
    Ohio State University, Columbus, Ohio
  • A. Mahmoud
    Ohio State University, Columbus, Ohio
  • C. J. Roberts
    Ophthalmology and Biomedical Engineering, The Ohio State University, Columbus, Ohio
  • Footnotes
    Commercial Relationships  J.R. Lewis, Ziemer Group, F; Ziemer USA, E; Ziemer Group, R; A. Mahmoud, Ziemer Group, P; C.J. Roberts, Ziemer Group, C; Ziemer Group, P; Ziemer Group, R.
  • Footnotes
    Support  None.
Investigative Ophthalmology & Visual Science April 2010, Vol.51, 5651. doi:
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      J. R. Lewis, A. Mahmoud, C. J. Roberts; Recentration to the Pupil Center Provides Consistency of Central Anterior Curvature Calculation Under Conditions of Misalignment. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5651.

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

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Purpose: : To examine the effect of pupil recentration on central anterior curvature calculation in purposefully misaligned topographic maps.

Methods: : Two series of anterior segment optical images of 11 eyes of 10 subjects were collected with the Galilei Dual Scheimpflug Analyer (Ziemer Group) of normal eyes under the condition of normal alignment and repeated with a calibrated 1-mm horizontal misalignment. The average central anterior curvatures over the central 4 mm diameter zone were recorded for the following conditions: normal manual alignment and not re-centered to pupil (C-ncp), normal manual alignment and re-centered to pupil (C-cp), calibrated decentration and not centered to pupil (D-ncp), and calibrated decentered and re-centered to pupil (D-cp). The conditions C-ncp vs C-cp, D-ncp vs D-cp, and C-cp vs D-cp were statistically compared with t-tests. A Bonferroni correction for multiple comparisons was used to set the significance threshold a priori at p<0.017.

Results: : Significant differences were found for C-ncp vs C-cp (mean difference -0.11, range -0.41 to 0.06 D; p = 0.012) and D-ncp vs D-cp (mean difference 0.33 D, range -0.29 to 0.84 D; p = 0.0023), indicating that pupil recentration alters the central zone from the relative apex of acquisition to the pupil, in both aligned and misaligned conditions. However, C-cp and D-cp showed no significant difference (mean difference 0.12 D, range -0.32 to 0.36 D; p > 0.017), indicating that pupil recentration under both aligned and misaligned conditions produces consistent results.

Conclusions: : Recentration of topographic curvature calculations to the pupil center provides a consistent approach to evaluation of central topographic parameters, even under conditions of misalignment. Pupil re-centration may provide an advantage in comparing topographic maps acquired under varying circumstances.

Keywords: topography 

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