Previous studies have shown that the neurodegenerative changes in Parkinson disease also affect the oculomotor control system. In this report the authors used modern eye tracking technology to assess oculomotor control in 112 patients with Parkinson disease, including 18 de novo untreated patients, and 60 age-matched controls. Oculomotor function was compared between groups during fixation and while tracking a randomly displaced target on a PC monitor.
All patients with Parkinson disease and 2 of the 60 control subjects exhibited persistent ocular tremor that prevented stability during fixation. During fixations, the eyes of patients with Parkinson disease constantly rhythmically move at an average frequency of 5.7 Hz, in small amplitude, complex oscillations. The amplitude and frequency of fixation instability did not correlate with disease duration, clinical Unified Parkinson’s Disease Rating Scale (UPDRS) scores, or dopa-equivalent dosing. No differences in oculomotor parameters were found between medicated and unmedicated patients with Parkinson disease.
The authors suggest that the pervasiveness and specificity of this feature in Parkinson patients could provide a valuable early physiological biomarker for diagnosing Parkinson disease.
Gitchel GT, Wetzel PA, Baron MS: Pervasive Ocular Tremor in Patients With Parkinson Disease. Arch. Neurology [Epub ahead of print, April 9, 2012; doi:10.1001/archneurol.2012.70].
