title: Prevalence of dry eye syndrome after a three-year exposure to a clean room.
abstract: OBJECTIVE
  To measure the prevalence of dry eye syndrome (DES) among clean room (relative humidity ≤1%) workers from 2011 to 2013.
  
  
  METHODS
  Three annual DES examinations were performed completely in 352 clean room workers aged 20-40 years who were working at a secondary battery factory. Each examination comprised the tear-film break-up test (TFBUT), Schirmer's test I, slit-lamp microscopic examination, and McMonnies questionnaire. DES grades were measured using the Delphi approach. The annual examination results were analyzed using a general linear model and post-hoc analysis with repeated-ANOVA (Tukey). Multiple logistic regression was performed using the examination results from 2013 (dependent variable) to analyze the effect of years spent working in the clean room (independent variable).
  
  
  RESULTS
  The prevalence of DES among these workers was 14.8% in 2011, 27.1% in 2012, and 32.8% in 2013. The TFBUT and McMonnies questionnaire showed that DES grades worsened over time. Multiple logistic regression analysis indicated that the odds ratio for having dry eyes was 1.130 (95% CI 1.012-1.262) according to the findings of the McMonnies questionnaire.
  
  
  CONCLUSIONS
  This 3-year trend suggests that the increased prevalence of DES was associated with longer working hours. To decrease the prevalence of DES, employees should be assigned reasonable working hours with shift assignments that include appropriate break times. Workers should also wear protective eyewear, subdivide their working process to minimize exposure, and utilize preservative-free eye drops.
authors.affiliation: Department of Occupational & Environmental Medicine, Eulji University Hospital, Daejeon, South Korea.
authors.forename: Hyun A
authors.initials: HA
authors.lastname: Cho
authors.affiliation: Department of Occupational & Environmental Medicine, Eulji University Hospital, Daejeon, South Korea.
authors.forename: Jae Jung
authors.initials: JJ
authors.lastname: Cheon
authors.affiliation: Department of Occupational & Environmental Medicine, Eulji University Hospital, Daejeon, South Korea.
authors.forename: Jong Seok
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Department of Occupational & Environmental Medicine, Eulji University Hospital, Daejeon, South Korea.
authors.forename: Soo Young
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Department of Occupational & Environmental Medicine, Eulji University Hospital, Daejeon, South Korea.
authors.forename: Seong Sil
authors.initials: SS
authors.lastname: Chang
keywords: Clean rooms; Dry eye syndromes; Humidity; Tear film