MONDAY, April 9 (HealthDay News) -- Persistent eye tremors appear to be common in people with Parkinson's disease. The tremors affect a person's eye stability while tracking moving objects, a new study finds.

The findings suggest that testing eyeball movement -- "oculomotor testing" -- could help provide an early marker for diagnosing the nervous-system disease, the researchers said.

For the study, published online April 9 in the journal Archives of Neurology, researchers tested oculomotor function in 112 Parkinson's disease patients and a group of 60 healthy people by having them track a moving target on a computer screen.

All 112 Parkinson's patients, whether on medication or not, had persistent eye tremors that prevented them from keeping their eyes stable while following the target. The problem was observed in only two of the people in the "healthy" group, the investigators found.

That eye tremors and stability problems occurred even in Parkinson's patients on medication suggests the tremors are linked to the disease and not caused by medication, the study authors noted.

"All patients with [Parkinson's disease] exhibited persistent ocular tremor that prevented stability during fixation," concluded George Gitchel, of the Southeast Parkinson's Disease Research, Education, and Clinical Center at Hunter Holmes McGuire VA Medical Center in Richmond, Va., and colleagues.

"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]," the team noted in a journal news release.

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