International Journal of Keratoconus and Ectatic Corneal Diseases

Register      Login

VOLUME 1 , ISSUE 3 ( September-December, 2012 ) > List of Articles

RESEARCH ARTICLE

Comparative Evaluation of Elevation, Keratometric, Pachymetric and Wavefront Parameters in Normal Eyes, Subclinical Keratoconus and Keratoconus with a Dual Scheimpflug Analyzer

Joseph Colin, David Smadja, David Touboul

Citation Information : Colin J, Smadja D, Touboul D. Comparative Evaluation of Elevation, Keratometric, Pachymetric and Wavefront Parameters in Normal Eyes, Subclinical Keratoconus and Keratoconus with a Dual Scheimpflug Analyzer. Int J Kerat Ect Cor Dis 2012; 1 (3):158-166.

DOI: 10.5005/jp-journals-10025-1031

Published Online: 01-12-2012

Copyright Statement:  Copyright © 2012; Jaypee Brothers Medical Publishers (P) Ltd.


Abstract

Purpose

To compare the corneal parameters in normal corneas, forme fruste keratoconus (FFKC) and keratoconus measured with a dual Scheimpflug analyzer.

Materials and methods

A total of 372 eyes of 197 patients were prospectively enrolled in the study and divided into three groups: 148 eyes of 102 patients with keratoconus, 47 contralateral topographically normal eyes of clinically evident keratoconus in the fellow eye and 177 eyes of 95 refractive surgery candidates with normal corneas. All eyes were measured with a dual Scheimpflug analyzer and elevation, keratometric, pachymetric and wavefront data were analyzed. Mean and intergroup comparisons were performed for 43 parameters.

Results

Eighty-eight percent of the parameters analyzed (38/43) were significantly different between normal and keratoconus whereas it was less than 40% (17/43) between normal and FFKC. The majority of the elevation parameters were significantly different between normal eyes and FFKC (11/14) whereas the I-S value and the Kmax were the only two parameters related to the anterior curvature that were significantly different between both groups. Corneal vertical coma was the only corneal aberrations significantly different between normal and FFKC (p < 0.07).

Conclusion

The dual Scheimpflug analyzer provides useful parameters for differentiating normal corneas, FFKC and keratoconus.

How to cite this article

Smadja D, Touboul D, Colin J. Comparative Evaluation of Elevation, Keratometric, Pachymetric and Wavefront Parameters in Normal Eyes, Subclinical Keratoconus and Keratoconus with a Dual Scheimpflug Analyzer. Int J Kerat Ect Cor Dis 2012;1(3):158-166.


PDF Share
  1. Contribution of the corneal epithelium to anterior corneal topography in patients having myopic photorefractive keratectomy. J Cataract Refract Surg 2007;33(11):1860-65.
  2. Epithelial, stromal, and total corneal thickness in keratoconus: Three-dimensional display with artemis very-high frequency digital ultrasound. J Refract Surg 2010;26(4):259-72.
  3. Comparison of front- surface corneal topography and Bowman membrane specular topography in keratoconus. J Cartaract Refract Surg 2012;38(6):1043-49.
  4. Topographic and tomographic properties of forme fruste keratoconus corneas. Invest Ophthalmol Vis Sci 2010;51(11):5546-55.
  5. Corneal-thickness spatial profile and corneal-volume distribution: Tomographic indices to detect keratoconus. J Cartaract Refract Surg 2006 Nov;32:1851-59.
  6. Novel pachymetric parameters based on corneal tomography for diagnosing keratoconus. J Refract Surg 2011;27(10):753-58.
  7. Detection of subclinical keratoconus by using corneal anterior and posterior surface aberrations and thickness spatial profiles. Invest Ophthalmol Vis Sci 2010;51(7):3424-32.
  8. Corneal volume, pachymetry, and correlation of anterior and posterior corneal shape in subclinical and different stages of clinical keratoconus. J Cataract Refract Surg 2010;36(5):814-25.
  9. Use of a support vector machine for keratoconus and subclinical keratoconus detection by topographic and tomographic data. Ophthalmology 2012;119:2231-38.
  10. Longitudinal study of the normal eyes in unilateral keratoconus patients. Ophthalmology 2004;111(3):440-46.
  11. Keratoconus. Surv Ophthalmol 1998;42(4):297-319.
  12. Baseline findings in the collaborative longitudinal evaluation of keratoconus (CLEK) study. Invest Ophthalmol Vis Sci 1998;39:2537-46.
  13. Qualitative and quantitative analysis of aspheric symmetry and asymmetry on corneal surfaces. Boston (MA): Electronic Poster, ASCRS Symposium and Congress 2010 April; 9-14.
  14. Influence of the reference surface shape for discriminating between normal corneas, subclinical keratoconus and keratoconus. J Refract Surg 2013 (In review).
  15. Corneal elevation topography: Best fit sphere, elevation distance, asphericity, toricity and clinical implications. Cornea 2011;30(5):508-15.
  16. The role of reference body selection in calculating posterior corneal elevation and prediction of keratoconus using rotating Scheimpflug camera. Acta ophthalmologica 2011;89(3):e251-56.
  17. Corneal ectasia risk score: Statistical validity and clinical relevance. J Refract Surg 2010;26(4):238-41.
  18. Comparison of and correlation between anterior and posterior corneal elevation maps in normal eyes and keratoconus-suspect eyes. J Refract Surg 2007:789-95.
  19. Comparative evaluation of refractive surgery candidates with Placido topography, Orbscan II, Pentacam and wavefront analysis. J Cartaract Refract Surg 2008;34:623-31.
  20. Evaluation of keratoconus in Asians: role of Orbscan II and Tomey TMS-2 corneal topography. Am J Ophthalmol 2007;143(3):390-400.
  21. Percentage thickness increase and absolute difference from thinnest to describe thickness profile. J Refract Surg 2010 Feb;26(2):84-86.
  22. Defining subclinical keratoconus using corneal first-surface higher-order aberrations. Am J Ophthalmol 2007;143(3):381-89.
  23. Evaluation of total and corneal wavefront high order aberrations for the detection of forme fruste keratoconus. Invest Ophthalmol Visual Sci 2012;(C):2978-92.
  24. Corneal higher order aberrations: A method to grade keratoconus. J Refract Surg 2006;22(June):539-46.
  25. Association of corneal indices for the detection of ectasia-susceptible corneas. J Refract Surg 2012;28(3):166-67.
  26. Evaluation of Scheimpflug imaging parameters in subclinical keratoconus, keratoconus, and normal eyes. J Cataract Refract Surg 2011;37(6):1116-24.
PDF Share
PDF Share

© Jaypee Brothers Medical Publishers (P) LTD.