Visual dysfunction in Parkinson disease without dementia

Objective: To determine the profiles of visual dysfunction and their relationship to motor and cognitive dysfunction and to disability in mild to moderate Parkinson disease (PD) without dementia. Methods: Seventy-six independently living participants with mild to moderate PD and 161 neurologically normal older adults were studied using a comprehensive battery to assess visual acuity, contrast sensitivity (CS), visual speed of processing and attention, spatial and motion perception, visual and verbal memory, visuoconstructional abilities, executive functions, depression, and motor function. Results: Participants with PD scored significantly worse on all tests of vision and cognition compared with normal elderly persons. Reduced CS contributed to deficits on tests of spatial and motion perception and attention in participants with PD. Impairments in visual attention and spatial perception predicted worse cognitive function. Worse performances on tests of visual speed of processing and attention, spatial and motion perception, visual construction, and executive functions correlated with measures of postural instability and gait difficulty (in the Motor section of the Unified Parkinson's Disease Rating Scale). Impairments in motor function, visual memory, mood, and executive functions predicted worse disability as measured by Schwab-England Activities of Daily Living Scale. Conclusions: Patients with mild to moderate Parkinson disease showed impaired visual perception and cognition compared with elderly control subjects. Visual dysfunction contributes to parkinsonian disability through its influences on cognition and locomotion.