Computer Analysis of Smooth Pursuit Eye Movements

Abstract

Each input-output pathway of the oculomotor control system is made by a number of neural circuits. Some circuits are specific to the input considered, others are shared among several inputs depending on type of eye movement being evoked, and the remaining circuits belong to common input-output pathways for all types of eye movements. When eye movement analyses are made for diagnostic purposes, complex patterns of eye movements should be considered and/or subtle pathological modifications should be recognized. Smooth pursuit eye movements can be elicited by asking the subject to track a small target moving slowly in line of sight. Due to the static and dynamic limitations of the smooth pursuit control system, correcting saccades are frequently required to foveate the target when target velocity exceeds 50–60 deg/sec or in pathological situations. The eye movement recorded during tracking is then displayed. In order to reduce the effects of noise on the computation of eye velocity, eye position is smoothed before derivation.