title: Variables associated with corneal confocal microscopy parameters in healthy volunteers: implications for diabetic neuropathy screening.
abstract: OBJECTIVE
  Corneal confocal microscopy is a promising screening method for diabetic neuropathy. Although much research in this field has been accomplished, we aimed to determine and confirm the known clinical and eyewear variables associated with the parameters of corneal confocal microscopy specifically in healthy volunteers, in particular associations with corneal nerve fibre length.
  
  
  METHODS
  Clinical characteristics, electrophysiological examination and a general clinical eye history were collected from 64 healthy volunteers. Corneal confocal microscopy was performed to determine corneal nerve fibre length, corneal nerve branch density, corneal nerve fibre density and tortuosity coefficient. Univariate and multivariate linear regression analysis was used to determine clinical variables associated with corneal nerve fibre length parameters.
  
  
  RESULTS
  We observed that corneal nerve fibre length has a broad distribution in healthy volunteers (18 ± 4 mm/mm(2), 95% confidence interval, 12.3-25.7 mm/mm(2)). Multivariate regression analysis demonstrated that HbA(1c) was the only independent clinical factor to account for variations in corneal nerve fibre length, independent of age and status of contact lens wear.
  
  
  CONCLUSIONS
  This study does not provide convincing evidence that corneal nerve fibre length is independently associated with age or the wearing of contact lenses, and that these factors are therefore unlikely to hinder valid screening for polyneuropathies such as diabetic neuropathy. Furthermore, the strong inverse association of corneal nerve fibre length with glycaemic exposure may support the use of this parameter to detect subclinical pre-diabetic nerve injury.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, University of Toronto, Toronto, Canada.
authors.forename: T
authors.initials: T
authors.lastname: Wu
authors.forename: A
authors.initials: A
authors.lastname: Ahmed
authors.forename: V
authors.initials: V
authors.lastname: Bril
authors.forename: A
authors.initials: A
authors.lastname: Orszag
authors.forename: E
authors.initials: E
authors.lastname: Ng
authors.forename: P
authors.initials: P
authors.lastname: Nwe
authors.forename: B A
authors.initials: BA
authors.lastname: Perkins
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D003315:Cornea / Q000294:innervation* / Q000473:pathology*; D003430:Cross-Sectional Studies; D003929:Diabetic Neuropathies / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D018613:Microscopy, Confocal; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology; D012044:Regression Analysis
chemical_list: D015415:Biomarkers; D006442:Glycated Hemoglobin