title: Novel technique to measure horizontal corneal diameter using a Scheimpflug image on the Pentacam.
abstract: OBJECTIVE
  A new method to measure the horizontal corneal diameter using a Scheimpflug image (SFI) was introduced and compared with the automated iris camera photo (ICP) method on the Pentacam.
  
  
  METHODS
  Each one eye of 88 subjects without significant abnormality in the cornea was included. In SFI, diameters were measured manually using the built-in software tool with the edge-filter option. ICP value read from the overview display. Repeatability was determined from the first two measurements of each eye. The accuracy was assessed using Bland-Altman plot in comparison with caliper measurements.
  
  
  RESULTS
  The measurement failure rate of ICP was aggravated by pupil dilation, while that of SFI was unrelated to pupil dilation. Repeatability coefficients of ICP and SFI were 0.1mm and 0.12mm, respectively. The mean difference between ICP values and caliper values was not significant. SFI values were greater than caliper measurements by a mean of 0.13mm.
  
  
  CONCLUSIONS
  New SFI was reliable and could complement ICP in dilated pupil. The measurement failure rates of Pentacam need to be improved.
authors.affiliation: Department of Ophthalmology, CHA Bundang Medical Center, CHA University, 59 Yatap-ro, Bundang-gu, Seongnam-si, Gyeonggi-do 463-712, Republic of Korea.
authors.forename: Youngje
authors.initials: Y
authors.lastname: Sung
authors.affiliation: Department of Ophthalmology, CHA Bundang Medical Center, CHA University, 59 Yatap-ro, Bundang-gu, Seongnam-si, Gyeonggi-do 463-712, Republic of Korea.
authors.forename: Sokjoong
authors.initials: S
authors.lastname: Chung
authors.affiliation: Department of Ophthalmology, CHA Bundang Medical Center, CHA University, 59 Yatap-ro, Bundang-gu, Seongnam-si, Gyeonggi-do 463-712, Republic of Korea. Electronic address: forustous@cha.ac.kr.
authors.forename: Sang Min
authors.initials: SM
authors.lastname: Nam
mesh_terms: D003315:Cornea / Q000033:anatomy & histology*; D063171:Corneal Pachymetry / Q000295:instrumentation* / Q000379:methods; D019781:Corneal Topography / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D010781:Photography / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D000072776:Slit Lamp Microscopy / Q000295:instrumentation* / Q000379:methods
keywords: Horizontal white-to-white corneal diameter; Iris camera; Reliability; Scheimpflug image