title: Measuring visual discomfort in college students.
abstract: OBJECTIVE
  The purpose of this study was to measure the distribution visual discomfort symptoms in a group of college students using a survey developed by Conlon et al. and to analyze the type and frequency of symptoms in the subjects who display moderate to high amounts of visual discomfort to ascertain if this condition occurs along a single dimension or consists of different subtypes.
  
  
  METHODS
  Members of the research team administered a survey of visual discomfort developed by Conlon et al. (Conlon et al., Vis Cogn 1999;6:637-666) to 571 college students at the Claremont Colleges University over a 2-year period. The survey for measuring visual discomfort developed by Conlon consists of 23 items with a four-point scale (0 to 3) (see below). Scores on the survey can range from 0 to 69.
  
  
  RESULTS
  A Rasch analysis of the survey results showed that a single symptom dimension accounted for 73.5% of the variance. A principle component analysis of the residual variance from the Rasch analysis yielded three factors: factor 1 was associated with text movement and fading; factor 2 was associated with headache and soreness; and factor 3 was associated primarily with blur and diplopia.
  
  
  CONCLUSIONS
  The survey developed by Conlon is an appropriate measure of visual discomfort. In addition to the single dimension reported by Conlon, we found that some subjects with moderate to high amounts of visual discomfort tended to report particular types of symptoms. These results suggest that there may be multiple etiologies of visual discomfort.
authors: Southern California College of Optometry, Fullerton, California 92831, USA. eborsting@scco.edu
authors: Eric
authors: E
authors: Borsting
authors: Christopher H
authors: CH
authors: Chase
authors: William H
authors: WH
authors: Ridder
mesh_terms: D000328:Adult; D001248:Asthenopia / Q000175:diagnosis* / Q000209:etiology; D004172:Diplopia / Q000150:complications / Q000175:diagnosis; D005163:Factor Analysis, Statistical; D005260:Female; D006261:Headache / Q000150:complications; D006801:Humans; D008297:Male; D008960:Models, Psychological; D015233:Models, Statistical; D025341:Principal Component Analysis; D011594:Psychometrics / Q000379:methods; D013334:Students; D011795:Surveys and Questionnaires; D014495:Universities