(HealthDay News) – Ocular tremors, which prevent eye stability while fixating on a target, are pervasive among patients with Parkinson’s disease.

George T. Gitchel, from the Hunter Holmes McGuire Veterans Affairs Medical Center in Richmond, VA, and colleagues examined oculomotor control using modern precise eye tracking technology in 112 patients with Parkinson’s disease (including 18 untreated patients) and 60 age-matched controls.

The researchers found that all patients with Parkinson’s disease, but only two control subjects, showed oscillatory fixation instability (ocular tremor) while fixating on a target. There was no difference seen between cases and controls with respect to saccadic parameters and occurrence of square wave jerks. There was no correlation between the amplitude and frequency of the oscillatory fixation instability and disease duration, disease severity, or dopa-equivalent dosing. There was no difference between treated and untreated patients with Parkinson’s disease with respect to oculomotor parameters.

“All patients with Parkinson’s disease exhibited persistent ocular tremor that prevented stability during fixation,” Gitchel and colleagues conclude. “The pervasiveness and specificity of this feature suggest that modern, precise oculomotor testing could provide a valuable early physiological biomarker for diagnosing Parkinson’s disease.”

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