Stereopsis impairment is associated with decreased color perception and worse motor performance in Parkinson’s disease

BACKGROUND We conducted this study is to investigate the correlation between stereopsis dysfunction and color perception, as well as whether stereopsis impairment is associated with motor dysfunction in patients with Parkinson's disease (PD). METHOD Our present study included 45 PD patients and 50 non-PD control patients attending the Movement Disorder Center at Xuanwu Hospital Capital Medical University in Beijing from July 2011 to November 2011. Neurologic evaluations and visual function assessments were conducted, and the results between two groups of patients were compared. RESULTS We found that the total error scores (TESs) and partial error scores (PESs) for red, green, blue and purple were all significantly higher in PD patients than in control patients. The limited grade on the FLY Stereo Acuity Test with LEA Symbols was significantly lower in PD patients than in control patients (P = 0.0001), whereas the percentage of abnormal stereopsis in PD patients was significantly higher than in control patients (42.2% vs. 12%; P = 0.001). Multiple linear regression analysis showed that PD patients with higher Hoehn and Yahr Scale stage, and those with decreased stereopsis had higher Unified Parkinson's Disease Rating Scale (UPDRS) motor scores and worse motor function. Furthermore, our study demonstrates that the UPDRS motor scores and total average number of the Purdue Pegboard Test scores of PD patients were significantly improved when they had taken their medications, and the TESs and PESs for green were lower in when they were off their medications. CONCLUSION Our results provide more information on the underlying mechanisms of vision, motor and stereopsis impairments in PD patients.