title: Abnormal visual contrast acuity in Parkinson's disease.
abstract: BACKGROUND
  Low-contrast vision is thought to be reduced in Parkinson's disease (PD). This may have a direct impact on quality of life such as driving, using tools, finding objects, and mobility in low-light condition. Low-contrast letter acuity testing has been successful in assessing low-contrast vision in multiple sclerosis. We report the use of a new iPad application to measure low-contrast acuity in patients with PD.
  
  
  OBJECTIVE
  To evaluate low- and high-contrast letter acuity in PD patients and controls using a variable contrast acuity eye chart developed for the Apple iPad.
  
  
  METHODS
  Thirty-two PD and 71 control subjects were studied. Subjects viewed the Variable Contrast Acuity Chart on an iPad with both eyes open at two distances (40 cm and 2 m) and at high contrast (black and white visual acuity) and 2.5% low contrast. Acuity scores for the two groups were compared.
  
  
  RESULTS
  PD patients had significantly lower scores (indicating worse vision) for 2.5% low contrast at both distances and for high contrast at 2 m (p < 0.003) compared to controls. No significant difference was found between the two groups for high contrast at 40 cm (p = 0.12).
  
  
  CONCLUSIONS
  Parkinson's disease patients have reduced low and high contrast acuity compared to controls. An iPad app, as used in this study, could serve as a quick screening tool to complement more formal testing of patients with PD and other neurologic disorders.
authors.affiliation: Department of Neurology, University of Arizona, Tucson, AZ, USA.
authors.forename: Tanya P
authors.initials: TP
authors.lastname: Lin
authors.affiliation: Department of Neurology, Dalhousie University, Halifax, NS, Canada.
authors.forename: Heather
authors.initials: H
authors.lastname: Rigby
authors.affiliation: University of Arizona, Tucson, AZ, USA.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Adler
authors.affiliation: Department of Biostatistics, Mayo Clinic College of Medicine, Scottsdale, AZ, USA.
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Hentz
authors.affiliation: Department of Neurology, NYU School of Medicine, New York, NY, USA.
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Balcer
authors.affiliation: Department of Neurology, NYU School of Medicine, New York, NY, USA.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Galetta
authors.affiliation: King-Devick Test LLC, Oakbrook Terrace, IL, USA.
authors.forename: Steve
authors.initials: S
authors.lastname: Devick
authors.affiliation: King-Devick Test LLC, Oakbrook Terrace, IL, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Cronin
authors.affiliation: Department of Neurology, Mayo Clinic College of Medicine, Scottsdale, AZ, USA.
authors.forename: Charles H
authors.initials: CH
authors.lastname: Adler
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications*; D010468:Perceptual Disorders / Q000175:diagnosis / Q000209:etiology*; D010775:Photic Stimulation
keywords: Parkinson's disease; contrast sensitivity; vision; visual acuity