What Have We Learned From the Osaka Study?
To summarize the results of a cross-sectional epidemiologic study of Japanese office workers who use visual display terminals (VDTs). Workers in a pharmaceutical company head office were recruited. Participants were requested to complete a questionnaire on symptoms of dry eye disease (DED) and evaluations using the Work Limitations Questionnaire, International Physical Activity Questionnaire, Subjective Happiness Scale, and Pittsburgh Sleep Quality Index. Evaluations of ocular status, including conjunctival and corneal vital staining with lissamine green and fluorescein, measurement of tear film breakup time, and the Schirmer test, were performed. The Japanese 2007 diagnostic criteria for DED were implemented. The prevalence of DED among VDT workers was high. Definite DED was present in 11.6% (18.7% women and 8.0% men) of participants, and probable DED was present in 54.0% (57.8% women and 52.1% men). Total loss of workplace productivity was significantly greater in the definite DED group (4.82%) than in the probable DED group (4.06%) and the non-DED group (3.56%, P < 0.014, trend test). Participants with definite DED had significantly lower physical activity scores than those without DED (P = 0.025). Subjective happiness correlated with the dry eye symptom score (r = -0.188; P < 0.001). Participants with DED reported poor sleep quality at a higher rate compared with those without DED (45% vs. 34%), with a significant difference in the global score (P = 0.002). Dry eye is prevalent among VDT workers. Its impacts on work productivity, physical activity, and sleep quality warrant further study.