Saccades are rapid eye movements redirecting sight from one object of interest to another (Leigh & Zee,
2015). These movements are brief, rarely lasting more than 80 ms (Leigh & Zee,
2015). Advances in the study of anatomy and pathology of the brain and eye movements have reinforced the substantial utility of saccades in clinical practice. Abnormalities of saccades offer important clues in the diagnosis of a number of neurological disorders (Ramat, Leigh, Zee, & Optican,
2007). Quantitative saccade parameters include latency, amplitude, duration, peak velocity, and peak acceleration, etc. Among these measures, the peak velocity of saccades is of particular interest. Slow saccadic eye movements may suggest a brainstem lesion in excitatory saccade burst neurons (Horn & Büttner-Ennever,
1998; Horn, Büttner-Ennever, Suzuki, & Henn,
1995; Ramat, Leigh, Zee, Shaikh, & Optican,
2008). Examples of conditions that typically cause saccadic slowing include progressive supranuclear palsy (Chen et al.,
2010; Leigh & Riley,
2000) or spinocerebellar ataxia type 2 (Garbutt, Harwood, Kumar, Han, & Leigh,
2003; Wadia & Swami,
1971). Additional factors, such as saccade adaption and visual salience, may also affect saccade peak velocity (Ethier, Zee, & Shadmehr,
2008; Schütz, Braun, & Gegenfurtner,
2011); even subtle reductions in the peak velocity of otherwise normal saccades have been observed in states of mental fatigue (Di Stasi et al.,
2012). Thus, accurate determination of saccade peak velocity is critical to the understanding of normal and pathological saccade behavior.