title: Focused Tortuosity Definitions Based on Expert Clinical Assessment of Corneal Subbasal Nerves.
abstract: OBJECTIVE
  We examined agreement among experts in the assessment of corneal subbasal nerve tortuosity.
  
  
  METHODS
  Images of corneal subbasal nerves were obtained from investigators at seven sites (Auckland, Boston, Linköping, Manchester, Oslo, Rostock, and Sydney) using laser-scanning in vivo confocal microscopy. A set of 30 images was assembled and ordered by increasing tortuosity by 10 expert graders from the seven sites. In a first experiment, graders assessed tortuosity without a specific definition and performed grading three times, with at least 1 week between sessions. In a second experiment, graders assessed the same image set using four focused tortuosity definitions. Intersession and intergrader repeatability for the experiments were determined using the Spearman rank correlation.
  
  
  RESULTS
  Expert graders without a specific tortuosity definition had high intersession (Spearman correlation coefficient 0.80), but poor intergrader (0.62) repeatability. Specific definitions improved intergrader repeatability to 0.79. In particular, tortuosity defined by frequent small-amplitude directional changes (short range tortuosity) or by infrequent large-amplitude directional changes (long range tortuosity), indicated largely independent measures and resulted in improved repeatability across the graders. A further refinement, grading only the most tortuous nerve in a given image, improved the average correlation of a given grader's ordering of images with the group average to 0.86 to 0.90.
  
  
  CONCLUSIONS
  Definitions of tortuosity specifying short or long-range tortuosity and considering only the most tortuous nerve in an image improved the agreement in tortuosity grading among a group of expert observers. These definitions could improve accuracy and consistency in quantifying subbasal nerve tortuosity in clinical studies.
authors.affiliation: Department of Ophthalmology Institute for Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Neil
authors.initials: N
authors.lastname: Lagali
authors.affiliation: Department of Information Engineering, University of Padova, Padova, Italy.
authors.forename: Enea
authors.initials: E
authors.lastname: Poletti
authors.affiliation: Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
authors.forename: Dipika V
authors.initials: DV
authors.lastname: Patel
authors.affiliation: Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
authors.forename: Charles N J
authors.initials: CN
authors.lastname: McGhee
authors.affiliation: Ocular Surface Imaging Center, Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Pedram
authors.initials: P
authors.lastname: Hamrah
authors.affiliation: Ocular Surface Imaging Center, Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Kheirkhah
authors.affiliation: Centre for Endocrinology & Diabetes, Institute of Human Development, University of Manchester, Manchester, United Kingdom.
authors.forename: Mitra
authors.initials: M
authors.lastname: Tavakoli
authors.affiliation: Centre for Endocrinology & Diabetes, Institute of Human Development, University of Manchester, Manchester, United Kingdom 6Weill Cornell Medical College in Qatar, Qatar Foundation, Education City, Doha, Qatar.
authors.forename: Ioannis N
authors.initials: IN
authors.lastname: Petropoulos
authors.affiliation: Centre for Endocrinology & Diabetes, Institute of Human Development, University of Manchester, Manchester, United Kingdom 6Weill Cornell Medical College in Qatar, Qatar Foundation, Education City, Doha, Qatar.
authors.forename: Rayaz A
authors.initials: RA
authors.lastname: Malik
authors.affiliation: Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway 8Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.
authors.forename: Tor Paaske
authors.initials: TP
authors.lastname: Utheim
authors.affiliation: Department of Ophthalmology, University of Rostock, Rostock, Germany.
authors.forename: Andrey
authors.initials: A
authors.lastname: Zhivov
authors.affiliation: Department of Ophthalmology, University of Rostock, Rostock, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Stachs
authors.affiliation: Department of Ophthalmology, University of Rostock, Rostock, Germany.
authors.forename: Karen
authors.initials: K
authors.lastname: Falke
authors.affiliation: Department of Ophthalmology, University of Rostock, Rostock, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Peschel
authors.affiliation: Department of Ophthalmology, University of Rostock, Rostock, Germany.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Guthoff
authors.affiliation: School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Chao
authors.affiliation: School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Blanka
authors.initials: B
authors.lastname: Golebiowski
authors.affiliation: School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Fiona
authors.initials: F
authors.lastname: Stapleton
authors.affiliation: Department of Information Engineering, University of Padova, Padova, Italy.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Ruggeri
mesh_terms: D003315:Cornea / Q000294:innervation*; D006801:Humans; D018613:Microscopy, Confocal / Q000379:methods*; D009882:Ophthalmic Nerve / Q000473:pathology*; D014102:Torsion Abnormality / Q000175:diagnosis*