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

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.