Abstract:  Objective To analyze the consistency of Pentacam HR and Optovue iVue OCT in the measurement of corneal thickness in patients with keratoconus and myopia, and to provide guides for the measurement of corneal thickness in keratoconus and myopic patients. Design Diagnostic technique evaluation. Participants 181 cases (359 eyes) of keratoconus and myopia patients scheduled for refractive surgery from October 2018 to October 2020 in Beijing Tongren Hospital. 166 eyes were in the myopia group, and 193 eyes were in the keratoconus group. Methods Pentacam HR and Optovue iVue OCT were used to measure the thickness and related parameters of different cornea areas. A one-way analysis of variance or Kruskal-Wallis H test was used to analyze the differences. the Bland-Altman consistency test was used to analyze the consistency. The Spearman correlation coefficient was used to analyze the correlation between the differences and corneal surface morphological parameters. Main Outcome Measures Corneal thickness in central corneal thickness, the thinnest corneal thickness, maximum keratommetry (Kmax), index of surface variance (ISV), index of vertical asymmetry (IVA), index of height asymmetry(IHA), index of height decentration(IHD). Results In the myopia group and keratoconus group, the thinnest point and central thickness of the cornea measured by Optovue iVue OCT was about 20 μm lower than Pentacam HR on average, and the difference was statistically significant (all P<0.05). For the central and thinnest thickness in myopia group and keratoconus group, the consistency of the measurement results of the two measuring instruments are quite different. The difference both the central area and the thinnest part in myopia group was about 35 μm. The measured difference spans of the central area and the thinnest part in keratoconus group were 60 μm and 84.56 μm, respectively. Both myopia group and keratoconus group, the corneal thickness difference in the central area and the thinnest point had no obvious linear correlation with KMax, ISV, IVA, IHA, IHD. The central corneal thickness in myopia group: r=0.025, -0.15, -0.165, -0.104, -0.15; PIVA=0.034. However, the scatter plot showed no linear correlation, and the other P values all were >0.05. Conclusions The corneal thickness measured with Optovue iVue OCT is about 20 μm lower than with Pentacam HR. It is recommended to refer to the corneal thickness measured with Optovue iVue OCT for patients before refractive surgery and keratoconus cross-linking surgery. (Ophthalmol CHN, 2021, 30: 136-141)

Key words: keratoconus, corneal thickness, Pentacam HR；Optovue iVue OCT