Visual symptoms in Parkinson’s disease may remain largely unchanged despite treatment with levodopa or deep brain stimulation. This is according to new findings examining their impact on reading speed and contrast acuity.
Investigators assessed patients either prior to deep brain stimulation surgery or during their initial programming session. Participants were evaluated both off and on medication or with and without stimulation using standardized reading and color contrast tests. These tests measured rapid reading ability and sensitivity to high and low contrast across black, red, and yellow fields.
Results showed that reading speed and contrast acuity were not significantly altered after levodopa dosing or when stimulation was activated or deactivated. However, among patients who underwent testing both before and after surgery, there was a non-significant trend toward improved reading performance and sensitivity to black contrast at the lowest tested threshold.
The study highlights that current mainstay interventions in Parkinson’s disease may not meaningfully improve visual symptoms, which include difficulties with visuospatial processing, reading fluency, and contrast detection. These challenges are known to affect daily functioning and overall quality of life for patients. The findings suggest that while levodopa and deep brain stimulation remain central for managing motor symptoms, their effect on visual impairment is limited.
Researchers noted that the observation of possible improvement after surgery, although not statistically significant, points to an area for further investigation. Larger and more comprehensive studies are required to clarify whether subtle benefits may emerge over longer periods or under specific conditions.
The work underscores the need for innovative approaches to support visual function in Parkinson’s disease, particularly as vision-related quality of life continues to be an unmet therapeutic target.
Reference: Aslam S et al. Impact of levodopa and deep brain stimulation on visual impairments in Parkinson’s disease. Clin Park Relat Disord. 2025:13:100390.
