Ophthalmology in China ›› 2022, Vol. 31 ›› Issue (1): 51-56.doi: 10.13281/j.cnki.issn.1004-4469.2022.01.009

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The study on combination of Pentacam and Corvis ST for the diagnosis of forme frusta keratoconus

Zhang Hui 1, Tian Lei 2, 3, Qin Xiao1, Guo Lili 2, Zhang Di 1, Li Lin1, Zhang Haixia1   

  1. 1 School of Biomedical Engineering, Capital Medical University; Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Beijing 100069, China; 2 Beijing Tongren Eye Center, Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University; Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing 100730, China; 3 Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang University & Capital Medical University, Beijing Tongren Hospital, Beijing 100730, China 
  • Received:2020-11-03 Online:2022-01-25 Published:2022-01-18
  • Contact: Zhang Haixia, Email: Zhanghx@ccmu.edu.cn
  • Supported by:
    National Natural Science Foundation of China (32171304, 82171101); Beijing Nova Program (Z181100006218099); the Open Research Fund from Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beijing Tongren Hospital, Beihang University & Capital Medical University (BHTR-KFJJ-202001)

Abstract:  Objective To explore more combinations of corneal morphology and biomechanics for diagnosisof formefruste keratoconus, so as to explore more potential sensitive parameters. Design Diagnostic test. Participants Fifty patients (50 eyes) with forme frusta keratoconus and 50 patients (50 eyes) with pre-operative corneal refractive surgery were included. Methods  Receiver operating characteristic (ROC) curve was drawn to analyze the diagnostic efficiency of formefrustekeratoconus and Delong test was performed. The parameters of area under the ROC curve (AUC) greater than 0.70 were taken as independent variables, and Logistic regression model was established by the forward stepwise method to perform multivariate analysis on the diagnosis of forme fruste keratoconus. Main Outcome Measures Thinnest pachymetry (TP), tomographic and biomechanical index (TBI) and elastic modulus (E). Results Except for Km F, Astig F, Kmax F, A1V, A2T, A2V, HCT, PD, bIOP, there were statistical differences among the other parameters. TP had the highest diagnostic efficiency and AUC was 0.810. The forward stepwise Logistic regression was performed on the parameters with AUC exceeding 0.7, and the resulting model was as follows: CP=eβ/（1+eβ）（β=-0.063×TP-42.158×E+45.919）. The above analysis revealed that TP and E were the independent risk factors for the diagnosis of forme frusta keratoconus. ROC curve analysis showed that the AUC of this model was 0.916, which could significantly improve the diagnostic ability of forme frusta keratoconus (CP vs. TP: Z=2.796, P=0.0052; Delong test). Conclusion There is no significant difference between the diagnostic efficiency of corneal thinnest point thickness and TBI. In the early stage of keratoconus, the total mean curvature in the central 3 mm area of the cornea almost do not change but the difference between the inferior and superior curvature show an increasing trend.The role of corneal elastic modulus in the diagnosis of forme frusta keratoconus is worthy of attention and may be used as a supplementary parameter for disease assessment in the future. (Ophthalmol CHN, 2022, 31: 51-56)

Key words: Forme fruste keratoconus/diagnosis, morphology, biomechanics