Objective: To evaluate visual acuity at high and low contrast with five distinct colors (red, green, blue, yellow, and black) in Parkinson’s disease (PD) patients and controls using an iPad application.
Background: Changes in color vision and contrast sensitivity are a non-motor feature of PD. These changes can have a significant impact on activities such as driving and walking in low-light condition.
Design/Methods: Subjects were recruited from Mayo Clinic Arizona and the Arizona Study of Aging and Neurodegenerative Disorders. A movement examination, including the Movement Disorders Society Unified Parkinson’s Disease Rating Scale, was recorded on the day of vision testing. Visual acuity was tested with the Variable Contrast Acuity Chart (King-Devick Test LLC, Oakbrook Terrace, IL) on an Apple iPad 2. Subjects were tested at a comfortable reading distance (40 cms) using five distinct colors (red, green, blue, yellow, and black) at low (2.5%) and high (100%) contrast.
Results: 36 patients with PD (mean age 68 years) and 36 control subjects (mean age 72 years) were studied. The mean disease duration of PD was 6.4 ± 4.6 years, Hoehn and Yahr staging was 2.0 ± 0.6, MDS-UPDRS part II was 11.7 ± 7.0 and part III was 24.5 ± 9.9. After adjusting for age and gender, PD patients had significantly (p<0.05) lower scores at high (100%) as well as low (2.5%) contrast for all five colors tested except for yellow at low contrast (2.5%) (p=0.10).
Conclusions: PD patients have significantly reduced visual acuity for all the colors tested at various levels of contrast (except for yellow at low contrast) compared to controls. This test can serve as a useful tool for assessing vision in PD and has potential for being a biomarker to differentiate PD from controls.
- Visual sequelae of Parkinson’s Disease can have a significant impact on activities of daily living.
- In this study utilizing the tablet-based K-D Variable Contrast Sensitivity Chart, Parkinson’s Disease patients have worse visual acuity at both high (100%) and low (2.5%) contrast under colors black, red, blue and green.
- The K-D Variable Contrast Sensitivity Chart is a useful tool for assessing visual function in PD and has a biomarker to differentiate PD from controls.