title: Computer vision syndrome in presbyopia and beginning presbyopia: effects of spectacle lens type.
abstract: OBJECTIVE
  This office field study investigated the effects of different types of spectacle lenses habitually worn by computer users with presbyopia and in the beginning stages of presbyopia. Computer vision syndrome was assessed through reported complaints and ergonomic conditions.
  
  
  METHODS
  A questionnaire regarding the type of habitually worn near-vision lenses at the workplace, visual conditions and the levels of different types of complaints was administered to 175 participants aged 35 years and older (mean ± SD: 52.0 ± 6.7 years). Statistical factor analysis identified five specific aspects of the complaints. Workplace conditions were analysed based on photographs taken in typical working conditions.
  
  
  RESULTS
  In the subgroup of 25 users between the ages of 36 and 57 years (mean 44 ± 5 years), who wore distance-vision lenses and performed more demanding occupational tasks, the reported extents of 'ocular strain', 'musculoskeletal strain' and 'headache' increased with the daily duration of computer work and explained up to 44 per cent of the variance (rs = 0.66). In the other subgroups, this effect was smaller, while in the complete sample (n = 175), this correlation was approximately rs = 0.2. The subgroup of 85 general-purpose progressive lens users (mean age 54 years) adopted head inclinations that were approximately seven degrees more elevated than those of the subgroups with single vision lenses.
  
  
  CONCLUSIONS
  The present questionnaire was able to assess the complaints of computer users depending on the type of spectacle lenses worn. A missing near-vision addition among participants in the early stages of presbyopia was identified as a risk factor for complaints among those with longer daily durations of demanding computer work.
authors.affiliation: Leibniz Research Center for Working Environment and Human Factors, Dortmund, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Jaschinski
authors.affiliation: Leibniz Research Center for Working Environment and Human Factors, Dortmund, Germany.
authors.forename: Mirjam
authors.initials: M
authors.lastname: König
authors.affiliation: Leibniz Research Center for Working Environment and Human Factors, Dortmund, Germany.
authors.forename: Tiofil M
authors.initials: TM
authors.lastname: Mekontso
authors.affiliation: ZEISS Vision Science Lab, Carl Zeiss Vision International GmbH, Tübingen, Germany.
authors.forename: Arne
authors.initials: A
authors.lastname: Ohlendorf
authors.affiliation: Technology and Innovation, Carl Zeiss Vision GmbH, Aalen, Germany. jaschinski@iado.de.
authors.forename: Monique
authors.initials: M
authors.lastname: Welscher
mesh_terms: D000328:Adult; D003201:Computers; D018450:Disease Progression; D004867:Equipment Design; D005139:Eyeglasses; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011305:Presbyopia / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D011795:Surveys and Questionnaires; D013577:Syndrome; D014792:Visual Acuity / Q000502:physiology*
keywords: computer work; presbyopia; spectacle lenses