ObjectiveTo evaluate visual field changes in early mild Parkinson's disease. Methods A total of 66 eyes of 33 cases with early mild Parkinson's disease and 72 eyes of 36 age-matched normal individuals were enrolled into the study. Humphrey Field Analyzer II was applied for central visual field test. The visual field indices of mean deviation (MD) and pattern standard deviation (PSD) were analyzed to evaluate the location and the characteristics of visual field defect in this study. ResultsVisual field indices MD (-3.4±2.5) dB was significantly changed in patients with PD when compared to the controls (-0.6±1.7) dB. PSD (4.3±2.6) was significantly higher in patients with PD than that in the control group (2.1±1.8) dB. Glaucoma hemifield test (GHT) assessment was within normal limits in the controls. Of the 33 patients (66 eyes) in PD, GHT showed outside normal limits in 31 eyes, borderline in 8 eyes, and within normal limits in 27 eyes. 31 eyes outside normal limits appeared glaucomatous visual field defects, in which 16 with nasal step and 5 with arcuate defect. ConclusionsVisual field indices including MD and PSD in early mild patients with PD were significantly worse than that in the controls group. GHT abnormalities could be found in early mild PD patients with visual field defects, including pericentral scotoma and nasal step, which mimicked glaucomatous changes.