title: Reproducibility of straylight measurement by C-Quant for assessment of retinal straylight using the compensation comparison method.
abstract: BACKGROUND
  Straylight gives the appearance of a veil of light thrown over a person's retinal image when there is a strong light source present. We examined the reproducibility of the measurements by C-Quant, and assessed its correlation to characteristics of the eye and subjects' age.
  
  
  METHODS
  Five repeated straylight measurements were taken using the dominant eye of 45 healthy subjects (age 21-59) with a BCVA of 20/20: 14 emmetropic, 16 myopic, eight hyperopic and seven with astigmatism. We assessed the extent of reproducibility of straylight measures using the intraclass correlation coefficient.
  
  
  RESULTS
  The mean straylight value of all measurements was 1.01 (SD 0.23, median 0.97, interquartile range 0.85-1.1). Per 10 years of age, straylight increased in average by 0.10 (95%CI 0.04 to 0.16, p < 0.01]. We found no independent association of refraction (range -5.25 dpt to +2 dpt) on straylight values (0.001; 95%CI -0.022 to 0.024, p = 0.92). Compared to emmetropic subjects, myopia reduced straylight (-.011; -0.024 to 0.02, p = 0.11), whereas higher straylight values (0.09; -0.01 to 0.20, p = 0.09) were observed in subjects with blue irises as compared to dark-colored irises when correcting for age. The intraclass correlation coefficient (ICC) of repeated measurements was 0.83 (95%CI 0.76 to 0.90).
  
  
  CONCLUSIONS
  Our study showed that straylight measurements with the C-Quant had a high reproducibility, i.e. a lack of large intra-observer variability, making it appropriate to be applied in long-term follow-up studies assessing the long-term effect of surgical procedures on the quality of vision.
authors.affiliation: Jules-Gonin Eye Hospital, University of Lausanne, Avenue de France 15, 1000 Lausanne 7, Vaud, Switzerland. ivo.guber@fa2.ch
authors.forename: Ivo
authors.initials: I
authors.lastname: Guber
authors.forename: Lucas M
authors.initials: LM
authors.lastname: Bachmann
authors.forename: Josef
authors.initials: J
authors.lastname: Guber
authors.forename: Frank
authors.initials: F
authors.lastname: Bochmann
authors.forename: Alex P
authors.initials: AP
authors.lastname: Lange
authors.forename: Michael A
authors.initials: MA
authors.lastname: Thiel
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000503:physiopathology; D058453:Emmetropia / Q000502:physiology*; D005260:Female; D019466:Glare / Q000009:adverse effects; D006801:Humans; D006956:Hyperopia / Q000503:physiopathology; D008027:Light; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology; D009887:Ophthalmoscopy / Q000379:methods / Q000592:standards*; D010775:Photic Stimulation / Q000379:methods*; D012030:Refractive Errors / Q000503:physiopathology*; D015203:Reproducibility of Results; D012160:Retina / Q000502:physiology*; D012542:Scattering, Radiation; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult