Impact of levodopa and deep brain stimulation on visual impairments in Parkinson's disease

Parkinson's disease (PD) often causes visual changes that impair visuospatial processing, reading speed, and contrast acuity, impacting patients' quality of life.

This study aimed to investigate the effects of levodopa and deep brain stimulation (DBS) on visual symptoms associated with PD.

Patients were assessed either before DBS surgery (both off and on medication) or at their first DBS programming session (off medication, with and without stimulation). The King-Devick reading speed and color contrast visual tests were administered in each condition, evaluating high and low contrast across black, red, and yellow.

Reading speed and color contrast acuity did not change following levodopa dosing or when deep brain stimulation was off or on. However, those patients that had testing before and after DBS showed a non-significant trend towards improvement in their rapid reading test scores from pre-DBS to post-DBS and black color contrast sensitivity using the 2.5% contrast.

Although levodopa and DBS did not significantly improve reading speed or contrast acuity after single dosing or turning DBS on and off, in this small study, these findings provide valuable insights into the stability of these visual symptoms under current treatments. There was evidence that DBS surgery may improve certain aspects of reading speed and contrast acuity and further study is needed. This work underscores the need for innovative approaches to enhance visual function in PD.