Correction on the distortion of Scheimpflug imaging for dynamic central corneal thickness

Tianjie Li, Lei Tian, Like Wang, Ying Hon, Kwok Cheung Andrew Lam, Yifei Huang, Yuanyuan Wang, Yongping Zheng

Research output: Journal article publicationJournal articleAcademic researchpeer-review

15 Citations (Scopus)

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 ìm at highest concavity in 48 normal human corneas.
Original languageEnglish
Article number056006
JournalJournal of Biomedical Optics
Volume20
Issue number5
DOIs
Publication statusPublished - 1 May 2015

Keywords

  • central corneal thickness
  • Corvis ST
  • dynamic analysis
  • ray tracing
  • Scheimpflug imaging

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Biomedical Engineering

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