title: Comparison of an objective method of measuring bulbar redness to the use of traditional grading scales.
abstract: OBJECTIVE
  The primary objective was to compare measures of bulbar redness objectively using a photometric method with standard grading methods. Measures of redness were made on 24 participants wearing a silicone hydrogel contact lens in one eye for overnight wear. This report compares hyperaemia after 1 week of daily wear (baseline) with redness measured after 6 months of overnight wear.
  
  
  METHODS
  A new method of objectively measuring bulbar conjunctival redness was performed using the Spectrascan650 Photometer by Photo Research under fixed illumination. Photometric measures in CIEu(*) chromaticity values involve the measurement of chromaticity, a physical analogue of redness, greenness and blueness in the image. This method was validated in Part 1 of the study using repeated measurements on the photographic CCLRU scale. In Part 2 of the study, the photographic grading scale (CCLRU) from 0 (none) to 100 (extreme) was used to make the comparison.
  
  
  RESULTS
  Part 1 indicated that the photometer provides a repeatable and reliable measure of bulbar redness (CCC=0.989). A moderately strong and significant correlation was found between the CIEu(*) chromaticity values and the analogue data (R=0.795, p=0.000) at each measurement session (from baseline to 1 day, 1 week, and 1, 3 and 6 months of overnight wear).
  
  
  CONCLUSIONS
  This new standardized and objective method of measuring bulbar redness has great potential to replace subjective grading scales, especially with multi-centre studies, where variability between investigators occurs. This method may also detect smaller changes between visits or between eyes.
authors.affiliation: Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. gsorbara@scimail.uwaterloo.ca
authors.forename: Luigina
authors.initials: L
authors.lastname: Sorbara
authors.forename: Trefford
authors.initials: T
authors.lastname: Simpson
authors.forename: Stephanie
authors.initials: S
authors.lastname: Duench
authors.forename: Marc
authors.initials: M
authors.lastname: Schulze
authors.forename: Desmond
authors.initials: D
authors.lastname: Fonn
mesh_terms: D000328:Adult; D003228:Conjunctiva / Q000098:blood supply*; D018639:Contact Lens Solutions / Q000009:adverse effects; D018450:Disease Progression; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D006940:Hyperemia / Q000145:classification* / Q000175:diagnosis* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D012030:Refractive Errors / Q000628:therapy; D012720:Severity of Illness Index; D012826:Silicone Elastomers; D013053:Spectrophotometry / Q000295:instrumentation
chemical_list: D018639:Contact Lens Solutions; D012826:Silicone Elastomers; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate