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Clinical Trial
. 2018 Aug 20;8(1):12436.
doi: 10.1038/s41598-018-31008-1.

Comparison of Simulated Keratometry and Total Refractive Power for Keratoconus According to the Stage of Amsler-Krumeich Classification

Kazutaka Kamiya  1 , Yusuke Kono  2 , Masahide Takahashi  2 , Nobuyuki Shoji  2
Affiliations
Clinical Trial

Comparison of Simulated Keratometry and Total Refractive Power for Keratoconus According to the Stage of Amsler-Krumeich Classification

Kazutaka Kamiya et al. Sci Rep. .

Abstract

This study was aimed to assess the simulated keratometry (Sim K) and the total corneal refractive power (TCRP) in eyes with keratoconus with respect to the Amsler-Krumeich classification. We enrolled 100 eyes of 100 keratoconic patients and 25 age-matched normal eyes. The Sim K and TCRP were measured with a rotating Scheimpflug system (Pentacam HR, Oculus). The differences between Sim K and TCRP in the keratoconus group were significantly larger than those in the control group (p < 0.001). The differences between Sim K and TCRP became larger in the progressive stages of the disease (p = 0.191 for stage 1, p = 0.008 for stage 2, p < 0.001 for stage 3, p < 0.001 for stage 4). We found a significant correlation of Sim K with the differences between Sim K and TCRP in keratoconic patients (r = 0.497, p < 0.001). The differences between Sim K and TCRP for keratoconus were significantly larger than those for normal eyes, and the differences between Sim K and TCRP tended to become larger in the progressive stages of the disease. It is suggested that the Sim K readings overestimate the TCRP, especially in advanced keratoconus, and that this discrepancy is a possible source of a hyperopic refractive error after cataract surgery.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
The values of simulated keratometry (Sim K) and total corneal refractive power (TCRP) in the control and keratoconus groups according to the Amsler-Krumeich classification.
Figure 2
Figure 2
Graphs showing no significant association of simulated keratometry (Sim K) with the differences between Sim K and total corneal refractive power (TCRP) in the control group (Pearson correlation coefficient r = −0.109, p = 0.606), but a significant correlation in the keratoconus group (r = 0.497, p < 0.001).
Figure 3
Figure 3
Bland-Altman plots shows the difference between 2 measurements divided by mean of simulated keratometry (Sim K) and total corneal refractive power (TCRP) measurements in eyes with keratoconus. The solid lines represent mean differences between 2 consecutive measurements of corneal refractive power, dotted lines are the upper and lower borders of the 95% LoA (mean difference ± 1.96 multiplied by standard deviation of the mean difference.
See this image and copyright information in PMC

References

    1. Tan B, et al. How keratoconus influences optical performance of the eye. J Vis. 2008;13:1–10. - PubMed
    1. Leccisotti A. Refractive lens exchange in keratoconus. J Cataract Refract Surg. 2006;32:742–746. doi: 10.1016/j.jcrs.2006.01.063. - DOI - PubMed
    1. Thebpatiphat N, Hammersmith KM, Rapuano CJ, Ayres BD, Cohen EJ. Cataract surgery in keratoconus. Eye Contact Lens. 2007;33:244–246. doi: 10.1097/ICL.0b013e318030c96d. - DOI - PubMed
    1. Watson MP, et al. Cataract surgery outcome in eyes with keratoconus. Br J Ophthalmol. 2014;98:361–364. doi: 10.1136/bjophthalmol-2013-303829. - DOI - PubMed
    1. Kamiya K, et al. Predictability of Intraocular Lens Power Calculation for Cataract with Keratoconus: A Multicenter Study. Sci Rep. 2018;8:1312. doi: 10.1038/s41598-018-20040-w. - DOI - PMC - PubMed

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