Metric issues in the study of eye movements in psychiatry.

This review provides a description of the measurement methods, task definitions and measurement parameters in the study of smooth eye pursuit and saccade-antisaccade tasks in psychiatry. The large heterogeneity in task definitions and definitions of parameters and its potential impact on the large variability of the parameter measures is presented. Finally issues relating to data aggregation, practice effects and reliability of these smooth eye pursuit and saccade-antisaccade task performance measures are also discussed. The main conclusion of this review is that oculomotor function testing is still lacking standardization of methods, tasks and parameters affecting its usefulness in certain areas of psychiatric research. A future research program could derive a set of tentative recommendations for test standardization.