Investigation of Corneal Elevation, Astigmatism and Best Fit Sphere in Different stages of Keratoconus

Document Type : Original Article

Authors

1 Msc Student, Department of Optometry, Schoolof Rehabilitation, Shahid Beheshti University of Medical Science

2 MSc of Optometry, Eye research centre, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran

3 PhD, Department of Optometry, School of Rehabilitation, Shahid Beheshti University of Medical Science, Tehran, Iran

4 ophthalmologist, Eye Research center, Farabi Eye Hospital, Tehran University of Medical Science, Tehran, Iran

5 PhD student, Department of Optometry, School of Paramedicine, Mashhad University of Medical Science, Mashhad, Iran

6 Master of Science in Statistics, School of Rehabilitation Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran

Abstract

Purpose:
To investigate and determine the values of corneal elevation, astigmatism and best fit sphere (BFS) in anterior and posterior surfaces of the cornea in different stages of keratoconus (KCN) and to determine their differences and correlations
Methods:
In this retrospective study, 161 eyes of 161 KCN patients with mean age ± SD of 22.35 ± 6.10 years were examined using Pentacam HR (Oculus, Germany). Corrected distance visual acuity, spherical refractive error, astigmatism and outcomes of Scheimpflug-based imaging system were assessed based on the Amsler-Krumeich KCN classification.
Results:
The mean corrected distance visual acuity was different between all stages of KCN (Kruskal-Wallis, p≤0.001). Magnitude of corneal anterior and posterior BFS, elevation and astigmatism were different in 4 stages of KCN (Kruskal-Wallis test, P≤0.5). There were strong correlations between anterior and posterior astigmatism in grade 1 (p≤0.001, r=0.924), anterior and posterior elevation in grade 2 (p≤0.001, r=0.903) and anterior and posterior BFS in total group of KCN (p≤0.001, r=0.923).
Conclusion:
This study showed the values of corneal elevation, astigmatism and BFS in anterior and posterior surfaces of the cornea in different stages of KCN. Also, we determined strong correlation between some anterior and posterior parameters but not for all. Our findings can be used in clinical assessment of KCN.

Keywords

Main Subjects

References

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Journal of Paramedical Sciences & Rehabilitation
Volume 6, Issue 2
June 2017
Pages 38-47

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