Abstract: Objective To investigate the concentrations of matrix metalloproteinase-9(MMP-9) and tissue inhibitors of matrix metalloproteinase-1 (TIMP-1) in the tear of visual display terminal (VDT) users. Design Cross-sectional study. Participants VDT users of 45 cases (45 eyes). Method All the 45 VDT workers were divided into 3 groups according to the average work hours of VDT per day (group 1: VDT work time > 8 hours; group 2: VDT work time was 4~8 hours; group 3: VDT work time < 4 hours). Ocular Surface Disease Index (OSDI) questionnaire was performed. The ocular surface feature, prevalence of dry eye were evaluated by corneal vital staining with fluorescein, tear break-up time (BUT), and Schirmer test. MMP-9 and TIMP-1 concentrations (ng/ml) in tear were quantified with double antibodys and wichenzyme-linked immunosorbentassay (ELISA). Main Outcome Measures Score of the OSDI, BUT, Schirmer I, corneal fluorescein staining, concentration of MMP-9 and TIMP-1 in tear. Results The percentage of dry eye in VDT workers was 13.3%. There was significant difference in OSDI score among 3 groups (F=6.11, P=0.005): group 1 was higher than group 3 (P=0.003); there was no significant difference between group 2 and group 1(P=0.311), group 2 and group 3(P=0.319). There were no significant differences of TBUT, Schirmer I, corneal fluorescein staining in 3 groups (P=0.687, 0.122, 0.714). The mean concentration of MMP-9 and TIMP-1 in tear was significant difference among 3 groups (P =0.000). The concentration of MMP-9 and TIMP-1 in group 1 was 9.579±0.48 ng/ml and 3.174±0.29 ng/ml respectively, which both higher than group 2 (7.403±0.06 ng/ml and 2.286±0.28 ng/ml)(P=0.004, 0.005) and group 3(2.111±0.17 ng/ml and 0.391±0.06 ng/ml)(P=0.000). There were no significant differences in MMP-9 and TIMP-1 between before and after VDT work except in group 1 (P=0.04, 0.01). Conclusion Significant increase of MMP-9 and TIMP-1 concentration in tear in longer VDT work time group may be suggestive of time cumulative effect was contained. MMP-9 and TIMP-1 daily change in VDT workers maybe relate with dry eye.

Key words: text-indent: 0px, display: inline !important, font: medium Simsun, white-space: normal, float: none, letter-spacing: normal, color: rgb(0,0,0), word-spacing: 0px, -webkit-text-stroke-width: 0px">visual display terminal, dry eye, matrix metalloproteinase-9, tissue inhibitors of matrix metalloproteinase-1