Visual task complexity and age-related changes in saccadic eye movements
The goal of our study was to figure out the dynamic of neurodegeneration in healthy subjects, patients with Parkinson’s disease (PD) and progressive supranuclear palsy (PSP) and to compare processes of pathological neurodegeneration and normal aging. For these purposes we registered saccadic eye movements using electrooculography. 27 patients with PD, 5 patients with PSP and 52 healthy volunteers took part in the study. To analyze aging dynamic all participants were divided into matching age groups.
In healthy volunteers the mean saccade latency and the percentage of multistep saccades increase significantly after the age of 60. Values of these characteristics in patients with PD significantly exceed the values in the corresponding age groups of healthy subjects. The duration of single saccades depends on age to a smaller extent and does not change in patients with PD. In patients with PSP eye movement abnormalities are more salient than in patients with PD. Restriction of vertical gaze in PSP appears even on early stages of disease. As the disease progresses oculomotor abnormalities became more pronounced: decreasing of saccades amount, limitation of vertical and horizontal gaze and eye movements mismatch were revealed.
Thereby the saccades characteristics analysis allows us to reveal the rate of neurodegeneration that may be useful for early diagnostics and treatment control.