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 2m) 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 2m (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.

Summary Points:

  • High contrast and low contrast visual acuity was measured in individuals with Parkinson’s Disease (PD) and compared to controls.
  • Contrast acuity was measured with the King-Devick Variable Contrast Acuity Chart as an application on an iPad.
  • PD patients had significantly worse low contrast visual acuity (2.5% at 40 cm and 2 m) and worse high contrast acuity at far (100% at 2 m), compared to those without PD.
  • Low contrast acuity scores correlated with disease severity.

The K-D Variable Contrast Acuity Chart provides a portable, adjustable, quantitative measure of contrast visual acuity, and may reveal undiagnosed visual impairment in patients with PD, along with a use in monitoring PD severity.

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