Patients with Parkinson's disease (PD) commonly complain of impaired visual function and difficulty reading, despite normal visual acuity. Although previous studies have evaluated contrast sensitivity, color vision, visuospatial processing, visual hallucinations, and ocular movements, none has systematically evaluated the ocular complaints and ocular findings of PD patients. Thirty patients with early untreated PD and 31 control subjects without neurologic or known ocular diseases were ophthalmologically evaluated for the frequency of visual complaints, dry eyes, blepharitis, visual hallucinations, reduced blink rate, blepharospasm, and convergence insufficiency. Ocular complaints suggesting ocular surface irritation, altered tear film, visual hallucinations, blepharospasm, decreased blink rate, and decreased convergence amplitudes were more common in PD patients than in control subjects. These findings likely account for many of the visual difficulties commonly encountered by PD patients. These ocular abnormalities frequently respond to treatment.