title: Development of a new grading scale for tear ferning.
abstract: OBJECTIVE
  This paper reports on the development of a new tear ferning (TF) subjective grading scale, and compares it with the Rolando scale.
  
  
  METHODS
  TF patterns obtained from tear film samples collected from normal and dry eye subjects in previous studies were collated into a large image library. From this library, 60 images were selected to represent the full range of possible TF patterns, and a further sub-set of 15 images was chosen for analysis. Twenty-five optometrists were asked to rank the images in increasing order between extreme anchors on a scale of TF patterns. Interim statistical analysis of this ranking found 7 homogeneous sub-sets, where the image rankings overlapped for a group of images. A representative image (typically the mean) from each group was then adopted as the grade standard. Using this new 7-point grading scale, 25 optometrists were asked to grade the entire 60 image library at two sessions: once using the 4-point Rolando scale and once using the new 7-point scale, applying 0.25 grade unit interpolation.
  
  
  RESULTS
  Statistical analysis found that for the larger image set, the Rolando scale produced 3 homogeneous sub-sets, and the 7-point scale produced 5 homogeneous sub-sets. With this refinement, a new 5-point TF scale (Grades 0-4) was obtained.
  
  
  CONCLUSIONS
  The Rolando grading scale lacks discrimination between its Type I and II grades, reducing its reliability. The new 5-point grading scale is able to differentiate between TF patterns, and may provide additional support for the use of TF for both researcher and clinician.
authors.affiliation: Cornea Research Chair (CRC), Optometry Department, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia; Contact Lens and Anterior Eye Research (CLAER) Unit, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK. Electronic address: amasmali@ksu.edu.sa.
authors.forename: Ali M
authors.initials: AM
authors.lastname: Masmali
authors.affiliation: School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Murphy
authors.affiliation: School of Health Professions, Plymouth University, Plymouth, UK; Contact Lens and Anterior Eye Research (CLAER) Unit, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK.
authors.forename: Christine
authors.initials: C
authors.lastname: Purslow
mesh_terms: D000465:Algorithms; D003941:Diagnostic Techniques, Ophthalmological; D015352:Dry Eye Syndromes / Q000175:diagnosis* / Q000473:pathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D009093:Mucus / Q000737:chemistry / Q000166:cytology*; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013666:Tears / Q000737:chemistry / Q000166:cytology*; D064232:Visual Analog Scale
keywords: Dry eye; Grading scale; Tear ferning