Corneal elevation indices and pachymetry values of Saudi myopes using scheimpflug imaging

Objectives: To report the corneal elevation and thickness values for Saudi myopes and to evaluate the differences between these parameters in subgroups of this target population. Methods: Pentacam corneal topographic maps of the right eyes of patients visiting Al-Hokama Eye Clinic, Riyadh, Saudi Arabia, a tertiary eye center between January 2009 and December 2015 were retrospectively analyzed in this cross-sectional study. The patients were grouped into 3 categories based on their spherical readings: mild (-0.25 to -2.75D), moderate (-3.00 to -5.75D), and severe (>=-6.00D). Furthermore, patients with cylindrical readings of >=-1.00 diopter were categorized as having myopic astigmatism, whereas those with less than -1.00 cylindrical diopter were categorized as having simple myopia. Results: Our sample was comprised of 1,276 patients; 838 (65.7%) had simple myopia and 438 (34.3%) had myopic astigmatism. The values for the whole myopic group were as follows: anterior corneal elevation (AE) at the apex= 2.60 +/- 1.48 (standard deviation), thinnest AE= 2.56 +/- 1.68, posterior elevation (PE) at the apex= 3.67 +/- 3.58, thinnest PE= 4.92 +/- 3.81, central pachymetry= 550.09 +/- 34.29, apical pachymetry=550.73 +/- 34.64, and thinnest pachymetry= 546.30 +/- 34.61. All of the measurements, except the apical PE and thinnest PE, were statistically significant across the simple and myopic astigmatism groups (p<0.05). Comparing the mild to moderate myopia groups revealed a significant difference in the apical AE (p=0.037). Moreover, the comparison between the mild and severe myopia groups revealed that the apical PE and the thinnest PE, as well as the central, apical, and thinnest pachymetry values were statistically significantly different (p<0.05). Conclusion: The corneal elevation indices and thicknesses specific to the Saudi myopes were found to be comparable to the international databases in terms of the elevation and thickness in some of the parameters.