Objective: To investigate adult age-related changes in corneal thickness. Methods: In this cross-sectional study, one eye in each of 300 myopia and cataract outpatients at the Affiliated Hospital of Qingdao University from August to December, 2015 was studied. The patients were divided into three groups: Young (21 to 45 years old, [mean ± standard deviation] 26.4 ± 5.5 years, 96 eyes); Middle-aged (46 to 70 years old, 62.1±6.8 years, 86 eyes); and Elder (71 to 92 years old, 79.2 ± 5.6 years, 118 eyes). The Galilei Dual Scheimpflug Analyzer was used to measure corneal pachymetry. Central corneal thickness (CCT) and paracentral corneal thickness (PaCT) were evaluated by analysis of variance, and peripheral corneal thickness (PeCT) and thinnest corneal thickness (TCT) were analyzed by Kruskal-Wallis H rank-sum test. The relationship between the variables and age were analyzed by Pearson correlation analysis and Spearman correlation analysis. Results: There were no significant differences among the three groups in CCT and PaCT. Among the three groups there were significant differences in PeCT (H=39.12, P<0.001).The PeCT of the Young Group was thicker than both the Middle-aged Group (P =0.017) and the Elder Group (P <0.001), but the difference in thickness between the Middle-aged and Elder Groups was not significant (P=0.193). For TCT, there were significant differences among the three groups (H=31.63, P<0.001). The TCT of the Young Group was thicker than both the Middle-aged Group (P =0.002) and the Elder Group (P<0.001), and the TCT of the Middle-aged Group was thicker than the Elder Group (P =0.002).PeCT was weakly correlated with age in the Middle-aged Group (r=-0.288, P =0.007). Other variables were not correlated with age in any of the groups. In general, CCT and PaCT were not correlated with age. In contrast, PeCT and TCT were negatively correlated with age (r=-0.369, -0.343, P <0.001). Conclusions:As people age, PeCT and TCT tend to get thinner, while CCT and PaCT do not change significantly.