title: A differential color flicker test for detecting acquired color vision impairment in multiple sclerosis and diabetic retinopathy.
abstract: BACKGROUND
  Optic neuritis related to multiple sclerosis and diabetic retinopathy are relatively selective post-retinal and retinal vision disorders. Vision impairment in both conditions is reliably measured by testing critical fusion frequency (CFF).
  
  
  METHODS
  To examine color vision, we measured the CFF in response to red and blue stimuli, and tested CFF values in patients without evident vision impairment. To ensure that differences in CFF values in a given subject depended only on color perception we displayed red and blue flickering stimuli at equal luminance. CFF to red or blue stimuli were compared in patients with medical history of optic neuritis related to multiple sclerosis (post-retinal vision impairment), patients with diabetic retinopathy (retinal vision impairment) and healthy subjects.
  
  
  RESULTS
  The test procedure disclosed altered CFF values for red and blue stimuli in both groups of patients studied. The comparison between the two groups disclosed a prevalent CFF impairment for red stimuli in patients with optic neuritis related to multiple sclerosis and for blue stimuli in patients with diabetic retinopathy.
  
  
  CONCLUSIONS
  The differential color flicker test appears highly accurate in detecting color vision impairment. Comparison of the two color CFFs differentiates retinal from post-retinal visual disorders.
authors.affiliation: Department of Neurological Sciences, Sapienza University of Rome, v.le dell'Università 30, 00185 Rome, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Gregori
authors.forename: Odysseas
authors.initials: O
authors.lastname: Papazachariadis
authors.forename: Alfonsa
authors.initials: A
authors.lastname: Farruggia
authors.forename: Neri
authors.initials: N
authors.lastname: Accornero
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D003118:Color Perception / Q000502:physiology*; D003119:Color Perception Tests / Q000295:instrumentation / Q000379:methods*; D003117:Color Vision Defects / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000150:complications / Q000503:physiopathology; D005260:Female; D005425:Flicker Fusion / Q000502:physiology*; D006801:Humans; D008297:Male; D009103:Multiple Sclerosis / Q000150:complications / Q000503:physiopathology; D009902:Optic Neuritis / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D010775:Photic Stimulation / Q000295:instrumentation / Q000379:methods; D012680:Sensitivity and Specificity