Towards consensus on visual pursuit and visual fixation in patients with disorders of consciousness. A Delphi study

BACKGROUND: The aim of this Delphi study was to reach consensus about definition, operationalization and assessment of visual pursuit (VP) and visual fixation (VF). METHODS: In a three-round international Delphi study, clinical and research experts on disorders of consciousness indicated their level of agreement on 87 statements using a 5-point Likert scale. Consensus for agreement was defined by a median of 5, an interquartile range (IQR) ≤ 1, and ≥ 80% indicating moderate or strong agreement. RESULTS: Forty-three experts from three continents participated, 32 completed all three rounds. For VP, the consensus statements with the highest levels of agreement were on the term 'pursuit of a visual stimulus', the description 'ability to follow visually in horizontal and/or vertical plane', a duration > 2 s, tracking in horizontal and vertical planes, and a frequency of more than 2 times per assessment. For VF, consensus statements with the highest levels of agreement were on the term 'sustained VF', the description 'sustained fixation in response to a salient stimulus', a duration of > 2 s and a frequency of 2 or more times per assessment. The assessment factors with the highest levels of agreement were personalized stimuli, the use of eye tracking technology, a patient dependent time of assessment, sufficient environmental light, upright posture, and the necessity to exclude ocular/oculomotor problems. CONCLUSION: This first international Delphi study on VP and VF in patients with disorders of consciousness provides provisional operational definitions and an overview of the most relevant assessment factors