Patients with parkinson disease (PD) usually reduced the dose the levodopa after received deep brain stimulation (DBS). However, studies seldomly mentioned about the influences on non-motors systems after the reduction. Our study focused on the changes after DBS and attribute them to the levodopa variety.

We calculated that group sample sizes of 126 patients (63 in group 1; 63 in group 2) would provide 80% power to reject the null hypothesis of equal means when the mean difference is -5(10-15) with standard deviations of 10 for test group and 10 for control group at a two-sided alpha of 0.05. Given an anticipated dropout rate of 20%, total sample size required is 158 (79 in reduction; 79 in non-reduction group).

Written informed consent was obtained from all participants. After the baseline measurement, we informed the eligible patients the assigned randomization group with sealed opaque envelopes marked with the inpatient numbers .

Within 12 months after STN-DBS, the LEDD of the intervention group was consistent with that before operation, and gradually decreased under the guidance of physician according to the expert consensus of DBS after 12 months. The compliance problem was solved by determining the actual number of antiparkinsonian medications returned by participants.

Inclusion Criteria:

• Participants underwent neuro-ophthalmologic examinations, including ocular fundus photography, automated perimetry, and OCT. Patients undergoing deep brain stimulation (DBS) took an extra VIPD-Q after the operation.

Exclusion Criteria:

• secondary causes of parkinsonism, prior brain surgery (except DBS), glaucoma, intraocular surgery, diabetes and other diseases affecting the visual field or neurologic systems, and the current use of medications affecting visual function.