title: Evaluation of Melbourne Edge Test contrast sensitivity measures in the visually impaired.
abstract: OBJECTIVE
  Contrast sensitivity (CS) provides important information on visual function. This study aimed to assess differences in clinical expediency of the CS increment-matched new back-lit and original paper versions of the Melbourne Edge Test (MET) to determine the CS of the visually impaired.
  
  
  METHODS
  The back-lit and paper MET were administered to 75 visually impaired subjects (28-97 years). Two versions of the back-lit MET acetates were used to match the CS increments with the paper-based MET. Measures of CS were repeated after 30 min and again in the presence of a focal light source directed onto the MET. Visual acuity was measured with a Bailey-Lovie chart and subjects rated how much difficulty they had with face and vehicle recognition.
  
  
  RESULTS
  The back-lit MET gave a significantly higher CS than the paper-based version (14.2 +/- 4.1 dB vs 11.3 +/- 4.3 dB, p < 0.001). A significantly higher reading resulted with repetition of the paper-based MET (by 1.0 +/- 1.7 dB, p < 0.001), but this was not evident with the back-lit MET (by 0.1 +/- 1.4 dB, p = 0.53). The MET readings were increased by a focal light source, in both the back-lit (by 0.3 +/- 0.81, p < 0.01) and paper-based (1.2 +/- 1.7, p < 0.001) versions. CS as measured by the back-lit and paper-based versions of the MET was significantly correlated to patients' perceived ability to recognise faces (r = 0.71, r = 0.85 respectively; p < 0.001) and vehicles (r = 0.67, r = 0.82 respectively; p < 0.001), and with distance visual acuity (both r = -0.64; p < 0.001).
  
  
  CONCLUSIONS
  The CS increment-matched back-lit MET gives higher CS values than the old paper-based test by approximately 3 dB and is more repeatable and less affected by external light sources. Clinically, the MET score provides information on patient difficulties with visual tasks, such as recognising faces.
authors.affiliation: Neurosciences Research Institute, Aston University, Birmingham B4 7ET UK. j.s.w.wolffsohn@aston.ac.uk
authors.forename: James S
authors.initials: JS
authors.lastname: Wolffsohn
authors.forename: Frank
authors.initials: F
authors.lastname: Eperjesi
authors.forename: Genevieve
authors.initials: G
authors.lastname: Napper
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D014786:Vision Disorders / Q000503:physiopathology*; D014787:Vision Tests / Q000379:methods*; D015354:Vision, Low / Q000503:physiopathology; D014792:Visual Acuity / Q000502:physiology