Temporal Co-Variation between Eye Lens Accommodation and Trapezius Muscle Activity during a Dynamic Near-Far Visual Task

PLoS One. 2015 May 11;10(5):e0126578. doi: 10.1371/journal.pone.0126578. eCollection 2015.

Abstract

Near work is associated with increased activity in the neck and shoulder muscles, but the underlying mechanism is still unknown. This study was designed to determine whether a dynamic change in focus, alternating between a nearby and a more distant visual target, produces a direct parallel change in trapezius muscle activity. Fourteen healthy controls and 12 patients with a history of visual and neck/shoulder symptoms performed a Near-Far visual task under three different viewing conditions; one neutral condition with no trial lenses, one condition with negative trial lenses to create increased accommodation, and one condition with positive trial lenses to create decreased accommodation. Eye lens accommodation and trapezius muscle activity were continuously recorded. The trapezius muscle activity was significantly higher during Near than during Far focusing periods for both groups within the neutral viewing condition, and there was a significant co-variation in time between accommodation and trapezius muscle activity within the neutral and positive viewing conditions for the control group. In conclusion, these results reveal a connection between Near focusing and increased muscle activity during dynamic changes in focus between a nearby and a far target. A direct link, from the accommodation/vergence system to the trapezius muscles cannot be ruled out, but the connection may also be explained by an increased need for eye-neck (head) stabilization when focusing on a nearby target as compared to a more distant target.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Accommodation, Ocular*
  • Adult
  • Eye Diseases / physiopathology
  • Female
  • Humans
  • Male
  • Reaction Time
  • Superficial Back Muscles / physiology*
  • Young Adult

Grants and funding

This study was funded by internal funds from the University of Gävle and by external funding from the Swedish Research Council for Health, Working Life and Welfare, http://www.forte.se/en/ [2005-0488 to HR and 2009-1761 to HR and MF]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.