title: Reduction of asthenopia related to accommodative relaxation by means of far point stimuli.
abstract: OBJECTIVE
  To conduct an experimental investigation of the effect of accommodative relaxation using far point shift stimuli for the reduction of asthenopia.
  
  
  METHODS
  Twenty-two female students accommodated to a far point shift stimuli during a 2-min period immediately after a 15-min sustained task on a three-dimensional display. Before and after the trial, their accommodative step response and symptoms were assessed. The far point shift stimuli in the optical system, which were presented on a refractometer, were created by moving the target scenery images from far to near, lineally centred about the far point position of each eye. During 2 min of fixating on the far point shift stimuli, changes in refraction were recorded in the same eye.
  
  
  RESULTS
  While looking at the far point shift stimuli, 10 of 22 subjects had changes in refraction that showed a hypermetropic shift, and the other 12 subjects had changes in refraction that showed a myopic shift. The time taken for the accommodative step response from far to near post-trial in the myopic shift group was markedly prolonged, and the accommodative lag at the far target in the optometer was significantly increased. In the myopic shift group, the symptoms of "eye fatigue", "eye pain", "eye heaviness", and "eye dryness" also increased after the trial. In the hyperopic shift group, however, only the symptom of "eye dryness" increased, with no reduction of accommodation function.
  
  
  CONCLUSIONS
  We suggest that accommodative relaxation by accommodative far point shift stimuli is effective in the reduction of asthenopia.
authors.affiliation: Department of Ophthalmology, University of Occupational and Environmental Health Japan, Kitakyushu, Japan.
authors.forename: Tsuneto
authors.initials: T
authors.lastname: Iwasaki
authors.forename: Akihiko
authors.initials: A
authors.lastname: Tawara
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Miyake
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000328:Adult; D001248:Asthenopia / Q000517:prevention & control*; D005260:Female; D005795:Generalization, Stimulus; D006801:Humans; D006956:Hyperopia / Q000503:physiopathology; D009216:Myopia / Q000503:physiopathology; D012029:Refraction, Ocular / Q000502:physiology