Heavy lifting at work and risk of retinal detachment: a population-based register study in Denmark

OBJECTIVES: To investigate the relationship between rhegmatogenous retinal detachment (RRD) and frequent heavy lifting in a Danish working population through national register data. METHODS: A dynamic cohort of all men aged 20–59 years in Denmark was followed through the Danish Occupational Hospitalisation Register from 1995 to 2010 for diagnosed RRD. Occupational categories were classified according to their potential for heavy lifting in 4 main groups: heavy lifters, manual workers unlikely to be heavy lifters, other manual workers and non-manual workers unlikely to be heavy lifters. The age-standardised rate of diagnosed RRD for heavy lifting occupations was compared with that experienced by the other 3 occupational categories. Rate ratios (RRs) and 95% CIs were estimated through a Poisson regression model adjusted for calendar period and age group. RESULTS: The highest age-standardised rate of diagnosed RRD was recorded among non-manual workers performing occupational activities unlikely to be associated with heavy lifting (18.0 cases per 100 000 person-years). The RR for workers in jobs expected to entail a high frequency of heavy lifting compared with manual workers whose occupation was unlikely to be associated with heavy lifting was 0.91 (95% CI 0.73 to 1.14), while in comparison with other manual workers, it was 0.93 (95% CI 0.78 to 1.11). The RR compared with non-manual workers in occupations unlikely to entail heavy lifting was 0.51 (95% CI 0.43 to 0.60). CONCLUSIONS: These findings do not support an association of occupational heavy lifting with diagnosed RRD. The epidemiological evidence for this association is still inconclusive. Future studies should use a more specific measure of exposure to resolve the outstanding uncertainties.