Affiliations: Department of Neurology, University of Arizona, Tucson, AZ, USA | Department of Neurology, Dalhousie University, Halifax, NS, Canada | University of Arizona, Tucson, AZ, USA | Department of Biostatistics, Mayo Clinic College of Medicine, Scottsdale, AZ, USA | Department of Neurology, NYU School of Medicine, New York, NY, USA | King-Devick Test LLC, Oakbrook Terrace, IL, USA | Department of Neurology, Mayo Clinic College of Medicine, Scottsdale, AZ, USA
Note:  Correspondence to: Charles H. Adler, MD, PhD, Professor, Department of Neurology, Mayo Clinic College of Medicine, 13400 E Shea Blvd, Scottsdale, AZ 85259, USA. Tel: +1 480 301 8100; Fax: +1 480 301 8451; E-mail: [email protected]
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.