title: Reproducibility-repeatability of choroidal thickness calculation using optical coherence tomography.
abstract: OBJECTIVE
  To evaluate the repeatability and reproducibility of subfoveal choroidal thickness (CT) calculations performed manually using optical coherence tomography (OCT).
  
  
  METHODS
  The CT was imaged in vivo at each of two visits on 11 healthy volunteers (mean age, 35.72 ± 13.19 years) using the spectral domain OCT. CT was manually measured after applying ImageJ processing filters on 15 radial subfoveal scans. Each radial scan was spaced 12° from each other and contained 2500 A-scans. The coefficient of variability, coefficient of repeatability (CoR), coefficient of reproducibility, and intraclass correlation coefficient determined the reproducibility and repeatability of the calculation. Axial length (AL) and mean spherical equivalent refractive error were measured with the IOLMaster and an open view autorefractor to study their potential relationship with CT.
  
  
  RESULTS
  The within-visit and between-visit coefficient of variability, CoR, coefficient of reproducibility, and intraclass correlation coefficient were 0.80, 2.97% 2.44%, and 99%, respectively. The subfoveal CT correlated significantly with AL (R = -0.60, p = 0.05).
  
  
  CONCLUSIONS
  The subfoveal CT could be measured manually in vivo using OCT and the readings obtained from the healthy subjects evaluated were repeatable and reproducible. It is proposed that OCT could be a useful instrument to perform in vivo assessment and monitoring of CT changes in retinal disease. The preliminary results suggest a negative correlation between subfoveal CT and AL in such a way that it decreases with increasing AL but not with refractive error.
authors.affiliation: Department of Biological Sciences, SUNY State College of Optometry, New York, New York 10036, USA. abenavente@sunyopt.edu
authors.forename: Alexandra
authors.initials: A
authors.lastname: Benavente-Pérez
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Hosking
authors.forename: Nicola S
authors.initials: NS
authors.lastname: Logan
authors.forename: Dheeraj
authors.initials: D
authors.lastname: Bansal
mesh_terms: D000328:Adult; D001699:Biometry / Q000379:methods; D002829:Choroid / Q000033:anatomy & histology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008875:Middle Aged; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence; D055815:Young Adult