Flockerzi E, Xanthopoulou K, Goebels SC, et al. - Researchers conducted this retrospective cross-sectional study to analyze the keratoconus (KC) stage distribution at different ages within the Homburg Keratoconus Center (HKC). One thousand nine hundred seventeen corneae (1,000 patients) were allocated to decades of age, classified according to Belin’s ABCD KC grading system and the stage distribution has been analyzed. Data reported that 73% (n = 728) of the patients were males, 27% (n = 272) were females. Between 21 and 30 years (n = 585 corneae, 294 patients), the highest prevalence of KC occurred. A4|B4 (n = 451), A0|B0 (n = 311), A2|B4 (n = 242), A2|B2 (n = 189) and A1|B2 (n = 154) were the most frequent A|B combinations. The stage distributions were similar in all age groups. Early KC is more pronounced in the posterior than in the anterior corneal curvature, whereas advanced stages of posterior corneal curvature correlate with early and advanced stages of anterior corneal curvature. Therefore, this research highlights the necessity of posterior corneal surface assessment in KC as enabled by the ABCD grading system.