International Journal of Keratoconus and Ectatic Corneal Diseases

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VOLUME 5 , ISSUE 3 ( September-December, 2016 ) > List of Articles


Keratoconic Cone using its Keratometry, Decentration, and Thickness as Staging Parameters

Kyaw L Tu, Abdo K Tourkmani, Singaram Srinivas

Citation Information : Tu KL, Tourkmani AK, Srinivas S. Keratoconic Cone using its Keratometry, Decentration, and Thickness as Staging Parameters. Int J Kerat Ect Cor Dis 2016; 5 (3):99-104.

DOI: 10.5005/jp-journals-10025-1129

Published Online: 01-12-2011

Copyright Statement:  Copyright © 2016; The Author(s).



To propose a new system of keratoconus staging using a set of parameters describing the keratoconic cone.

Materials and methods

Retrospective case series study of 101 keratoconic eyes of 58 patients was undertaken. They all had complete eye examination including corneal topography (Oculus Pentacam). Kmean, Kmax, higher order aberrations (HOAs) root mean square (HOARMS) value, pachymetry at thinnest point and steepest corneal meridian were obtained from Pentacam. Apex to thinnest pachymetry distance (D) was calculated using trigonometry. Pearson correlation coefficients between Kmax and HOARMS, between D on the one hand and the adjusted angle of steepest meridian, Kmean and Kmax respectively on the other, were calculated.


There is a statistically significant positive correlation between Kmax and HOARMS (p < 0.00001). There is a negative correlation, a “horizontalization,” of the steep meridian with D increase, although it fell short of statistical significance (p = 0.07). D and Kmean (p = 0.003), and D and Kmax (p = 0.005) are significantly negatively correlated.


Kmax correlates with significant changes in HOAs. D correlates with corneal astigmatic meridian change and has a divergent path to Kmean and to Kmax. We propose a new keratometry, decentration, and thinnest pachymetry staging using the parameters Kmax (K), distance from the corneal apex to the thinnest pachymetry point (D), and corneal thickness at its thinnest point (T) to give a better, detailed description of a keratoconic cornea which could lead to improvements in assessment of its severity and treatment outcomes.

How to cite this article

Tu KL, Tourkmani AK, Srinivas S. Keratoconic Cone using its Keratometry, Decentration and Thickness as Staging Parameters. Int J Kerat Ect Cor Dis 2016;5(3):99-104.

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