Outdoor and Sea-Exposed Occupations Versus Indoor Work and the Risk of Dry Eye Disease: A Systematic Review of Comparative Occupational Studies

Background: Dry eye disease is common and is shaped partly by the working environment. Outdoor and sea-exposed workers face sunlight, wind and dust, whereas indoor workers face air conditioning and screens, yet the two settings have not been compared systematically. Objective: To compare dry eye disease between outdoor or sea-exposed workers and indoor workers, and to examine whether the direction of the association differs between symptom-based and sign-based definitions. Methods: PubMed/MEDLINE, Embase, Cochrane CENTRAL, Scopus and Web of Science were searched for comparative occupational studies. Two reviewers screened records, assessed full texts and appraised risk of bias with the JBI checklist for analytical cross-sectional studies, resolving disagreements by discussion. Findings were synthesised by direction of effect without meta-analysis, and certainty was rated with GRADE. Results: Of 1,646 records, 204 full-text reports were assessed and 12 cross-sectional studies (59,470 participants, seven countries) were included. All four studies that measured tear-film signs found shorter or more often abnormal tear break-up time in outdoor workers, with an adjusted odds ratio of 2.09 (95% CI 1.09 to 3.99) for abnormal break-up time in one. Both studies using composite definitions found more dry eye in outdoor work. Among occupational comparison studies that recruited outdoor and indoor workers directly, five of six found more dry eye symptoms in outdoor workers, including an age-adjusted odds ratio of 2.09 (1.11 to 3.93) in street sweepers. Two population surveys setting broad agricultural and fishery classes against white-collar work recorded fewer symptoms in the outdoor class. No study analysed fishers or seafarers separately. Risk of bias was low in two studies, moderate in six and high in four, and certainty was low to very low. Conclusion: The available evidence points towards poorer tear-film stability and more dry eye in outdoor workers than in comparable indoor workers, although its certainty is low to very low. Symptom comparisons need indoor comparators described by screen exposure, and maritime workers require direct study.