Table 3.

Eye movement abnormalities in various genetic parkinsonism syndromes.

Type of mutation	Characteristic eye movement abnormalities
PARK 1	Increased latency of horizontal and vertical saccades as well as antisaccades Frequent multiple vertical saccades instead of single one Poor gain of vertical saccades Reduced precision of vertical saccades Poor performance on tasks involving antisaccades
PARK 2	Decreased gain of horizontal and vertical saccades Poor performance on tasks involving antisaccades
PARK 6	Increased latency of horizontal saccades Frequent multistep vertical saccades
PARK 9	Increased latency of horizontal and vertical saccades as well as antisaccades Reduced gain, precision and velocity of horizontal and vertical saccades Frequent multiple vertical saccades instead of single one Poor performance on tasks involving antisaccades

(Adapted and modified from Pretegiani and Optican [21].)