title: Repeatability of measuring corneal subbasal nerve fiber length in individuals with type 2 diabetes.
abstract: OBJECTIVE
  To analyze the repeatability of measuring nerve fiber length (NFL) from images of the human corneal subbasal nerve plexus using semiautomated software.
  
  
  METHODS
  Images were captured from the corneas of 50 subjects with type 2 diabetes mellitus who showed varying severity of neuropathy, using the Heidelberg Retina Tomograph 3 with Rostock Corneal Module. Semiautomated nerve analysis software was independently used by two observers to determine NFL from images of the subbasal nerve plexus. This procedure was undertaken on two occasions, 3 days apart.
  
  
  RESULTS
  The intraclass correlation coefficient values were 0.95 (95% confidence intervals: 0.92-0.97) for individual subjects and 0.95 (95% confidence intervals: 0.74-1.00) for observer. Bland-Altman plots of the NFL values indicated a reduced spread of data with lower NFL values. The overall spread of data was less for (a) the observer who was more experienced at analyzing nerve fiber images and (b) the second measurement occasion.
  
  
  CONCLUSIONS
  Semiautomated measurement of NFL in the subbasal nerve fiber layer is highly repeatable. Repeatability can be enhanced by using more experienced observers. It may be possible to markedly improve repeatability when measuring this anatomic structure using fully automated image analysis software.
authors: Institute of Health and Biomedical Innovation and School of Optometry, Queensland University of Technology, Queensland, Australia. n.efron@qut.edu.au
authors: Nathan
authors: N
authors: Efron
authors: Katie
authors: K
authors: Edwards
authors: Nicola
authors: N
authors: Roper
authors: Nicola
authors: N
authors: Pritchard
authors: Geoff P
authors: GP
authors: Sampson
authors: Ayda M
authors: AM
authors: Shahidi
authors: Dimitrios
authors: D
authors: Vagenas
authors: Anthony
authors: A
authors: Russell
authors: Jim
authors: J
authors: Graham
authors: Mohammad A
authors: MA
authors: Dabbah
authors: Rayaz A
authors: RA
authors: Malik
mesh_terms: D000328:Adult; D001331:Automation; D003315:Cornea / Q000294:innervation*; D003924:Diabetes Mellitus, Type 2 / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D018613:Microscopy, Confocal; D009412:Nerve Fibers / Q000473:pathology*; D012720:Severity of Illness Index; D012984:Software