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Journal of Biomedical Optics • Open Access

Correction on the distortion of Scheimpflug imaging for dynamic central corneal thickness
Author(s): Tianjie Li; Lei Tian; Like Wang; Ying Hon; Andrew K. C. Lam; Yifei Huang; Yuanyuan Wang; Yongping Zheng

Paper Abstract

The measurement of central corneal thickness (CCT) is important in ophthalmology. Most studies concerned the value at normal status, while rare ones focused on its dynamic changing. The commercial Corvis ST is the only commercial device currently available to visualize the two-dimensional image of dynamic corneal profiles during an air puff indentation. However, the directly observed CCT involves the Scheimpflug distortion, thus misleading the clinical diagnosis. This study aimed to correct the distortion for better measuring the dynamic CCTs. The optical path was first derived to consider the influence of factors on the use of Covis ST. A correction method was then proposed to estimate the CCT at any time during air puff indentation. Simulation results demonstrated the feasibility of the intuitive-feasible calibration for measuring the stationary CCT and indicated the necessity of correction when air puffed. Experiments on three contact lenses and four human corneas verified the prediction that the CCT would be underestimated when the improper calibration was conducted for air and overestimated when it was conducted on contact lenses made of polymethylmethacrylate. Using the proposed method, the CCT was finally observed to increase by 66±34  μm at highest concavity in 48 normal human corneas.

Paper Details

Date Published: 20 May 2015
PDF: 9 pages
J. Biomed. Opt. 20(5) 056006 doi: 10.1117/1.JBO.20.5.056006
Published in: Journal of Biomedical Optics Volume 20, Issue 5
Show Author Affiliations
Tianjie Li, The Hong Kong Polytechnic Univ. (Hong Kong, China)
Lei Tian, The Hong Kong Polytechnic Univ. (Hong Kong, China)
Chinese PLA General Hospital (China)
Capital Medical Univ. (China)
Like Wang, The Hong Kong Polytechnic Univ. (Hong Kong, China)
Ying Hon, The Hong Kong Polytechnic Univ. (Hong Kong, China)
Andrew K. C. Lam, The Hong Kong Polytechnic Univ. (Hong Kong, China)
Yifei Huang, Chinese PLA General Hospital (China)
Yuanyuan Wang, Fudan Univ. (China)
Yongping Zheng, The Hong Kong Polytechnic Univ. (Hong Kong, China)

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