Abstract
Several types of saccadic intrusions have their own salient features, including the presence, absence or latency of intersaccadic intervals. Macrosquare-wave jerks are known to have a shorter latency of about 100 msec, suggesting the involvement of the non-visually guided reflex saccade. Spuare-wave jerks and macrosaccadic oscillations (MSOs) are generally considered to have normal intersaccadic intervals of 200 msec in the visually guided saccadic system. Conversely, Kase et al. documented a shorter latency of about 160 msec, indicating an increased gain in the corrective saccadic system in a patient with spinocerebellar degeneration and MSOs. Our recent electro-oculographic study also showed a mean intersaccadic interval of 129.5 msec in a myasthenia gravis patient with edrophonium induced MSOs. This short latency is similar to that of corrective saccades, and is consistent with our understanding that MSOs are a form of saccadic hypermetria that is followed by a sequence of corrective saccades to attain the target.
