Abstract
Purpose: :
Combined head and eye with trunk movement is routinely used in determining the visual field. Changes in surrounding conditions for the combination of eye and head movements in gaze shift movements cause changes in the use of neck and shoulder muscles.The individual relationship between head and eye movement influences the development of painful symptoms in neck and shoulder muscles if the individual relation (e.g. occupation-related) can not be realized.
Methods: :
If an object lateral to the foveola was to be centrally displayed, the necessary gaze movement can be made up of varying contributions of head and eye movements. The relationship of head and eye movements in gaze shift can be specified in the so-called Head-Eye-Mover-Quotient (HE-quotient) [Bard et al.; Essilor].In this study three different groups of subjects were investigated with the Vision Print System TM R; Essilor (group I: children, age 6 and 7 years; group II: children, age 12 years; group III: patients with neck-shoulder-pain-syndrome). The subjects had to look alternate at a centrally and two peripherally shinning diodes, provoking a gaze shift of 40 degrees to the left or right. An ultrasound system detects the horizontal head movement.Changes in HE-quotient in the different groups have been statistically compared by Post-Hoc-test.
Results: :
A significant difference in the HE-quotient was found out for group I compared to group II (p=0.001) and group I compared to group III (p=0.001).The group of patients with neck-shoulder-pain-syndrome shows a majority of 82% of subjects with part of head-movement lower than 50% in gaze shift - eye movement was predominantly. In the age group of 6 and 7 year old children, only subjects with part of head-movement over 50% in gaze shift were present.
Conclusions: :
With regards to distribution of the control mechanisms in both control and test population, it is conceivable that increasing the visual fixation (e.g. at computer workstations) would result in an altered modus of gaze movements. The accompanied increase in nerval activation of the neck muscles results in the development of the typical symptoms.
Keywords: vision and action • ocular motor control • visual fields