title: Comparison of choroidal thickness measured by two methods.
abstract: OBJECTIVE
  To examine the profile of the choroidal thickness (CT) in healthy myopia subjects and emmetropic participants by Heidelberg Eye explore software and Image J software so as to compare the agreement and reproducibility of the two methods.
  
  
  METHODS
  Thirty-six study participants (36 eyes) were enrolled in this research. The fovea and parafoveal region (the region of 6mm diameter of the fovea as center) of the images were selected by spectral domain optic coherence tomography (SD-OCT). The choroidal thickness was measured manually by the Heidelberg Eye explore software (version 5.3.3.0, Heidelberg Engineering) with a vertical line and the Image J software with a line vertical to the retinal pigment epithelial layer. The agreement and reproducibility of the two methods were described by the Bland-Altmann analysis.
  
  
  RESULTS
  As compared with Heidelberg Eye explore software (39.9186), the repeatability coefficient is lower calculated by Image J software (27.3525). The Bland-Altmann analysis showed that the limits of 95% CI of agreement analysis is -18.437-63.949µm and the upper limits of the precision of the 95% CI of agreement is between 16.102 and 111.796µm and the lower limits is range from -66.29-21.41µm, which reflected a great variations of the difference.
  
  
  CONCLUSIONS
  The repeatability and agreement of measurement implied by Image J software was better than the Heidelberg Eye explore software. The Image J software should be used for measuring the choroidal thickness in future study in China.
authors: Department of Ophthalmology, Tongji Hospital, Wuhan 430030, Hubei Province, China.
authors: Wei
authors: W
authors: Chen
authors: Zhi-Tao
authors: ZT
authors: Wang
authors: Hong
authors: H
authors: Zhang