The impact of chronic neck pain on oculomotor performance during near point convergence and Fitts's tasks

Visual disturbances and oculomotor deficits have been found to affect those with chronic neck pain. Near point convergence (NPC), a measurement of convergence insufficiency (CI), is affected by rotated positions of the neck in those with neck pain. Fitts’s Law holds true for the oculomotor system, but amplitude places a larger demand on the system compared to target width. An oculomotor Fitts’s task has not been observed in those with neck pain or when seated in different rotated positions. Therefore, the current study evaluated how oculomotor performance was affected by neck rotation in those with chronic neck pain and controls. Saccadic and convergence performance was then compared to identify if specific deficits exist for those with neck pain. Behavioural data was collected using an Eye Link 1000 eye tracker. An RAF ruler was used to measure NPC. Questionnaire data was collected including neck disability index (NDI) and convergence insufficiency symptom survey (CISS). Reaction time (RT) was found to have increased for targets at a smaller amplitude for the symptomatic group compared to asymptomatic, which may indicate difficulty of the superior colliculus to process the central vision and altered cervical afferent information. A significant difference was found between groups for NPC in a neutral and rotated left position, with a trend approaching significance for the rotated right position. Larger NPC scores in the symptomatic group provides evidence that neck pain alters convergence performance. A significant correlation was found between CISS scores and NPC scores, also between CISS and NDI scores. The correlation results indicate that the CISS scores are a potential method to identify convergence performance deficits. Additionally, those with a greater self reported neck disability score demonstrate larger CISS scores, indicative of increased CI symptoms. Overall, those with chronic neck pain have decreased oculomotor performance for convergence tasks and RT for saccadic tasks at smaller IDs. ...