Regarding elevation indices, they showed statistically significant differences among groups, except for PE from BFTE. However, after controlling for the SE effect, the latter index did not stand robust in correlation to age.
Although the primary aim of our study was not to evaluate the refractive error effect, our results revealed that after controlling for the SE effect, all the elevation indices, from either BFS or BFTE, were correlated with age.
The post hoc test showed that thick corneas "group 3" had higher statistically significant BE from BFS and BFTE than thin corneas "group 1" (P = 0.02 and 0.005, respectively) and than average thickness corneas "group 2" (P = 0.018 and 0.009, respectively).
After exclusion of the age, refraction, and Km effects, partial correlation tests demonstrated that TCT was correlated with BE from BFS (P = 0.001), BE from BFTE (P = 0.001), and PPI max (P = 0.002).