Migration study of lens opacities in Bangladeshi adults in London and Bangladesh: a pilot study.

BACKGROUND: Lens opacities (LO) occur at an earlier age and have a higher prevalence in developing countries. In this pilot study, we assessed the feasibility and practical challenges of conducting a migration study, testing the hypothesis that migration from Bangladesh to the UK decreases the amount of LO on account of less exposure to adverse environmental factors. METHODS: The sample, which was selected from East London, UK and in Bangladesh, underwent detailed examination and lens grading by the same certified grader using Lens Opacification Classification System III. Data were analysed using univariate and multivariable logistic regression analyses. RESULTS: Considerable difficulties were encountered in recruiting the sample in both locations. 372 Bangladeshis aged 40-70 years were examined: 131 in London and 241 in Bangladesh. Having never migrated from Bangladesh was an independent risk factor for opacities (OR 7.6; 95% CI 3.6 to 15.9; p=0.001) as were age (OR 7.1; 95% CI 4.0 to 12.7; p=0.001) and diabetes (OR 2.5; 95% 1.0 to 6.0; p=0.04). The odds of LO were lower among those who had lived in the UK for a higher proportion of their life (OR 0.96; 95% CI 0.93 to 0.99; p=0.01), but this was not significant after adjusting for age and diabetes (OR 0.97; 95% CI 0.94 to 1.01; p=0.16). DISCUSSION: The study highlights the challenges of migration studies, and of studies involving ethnic minorities. Preliminary findings suggest that migration to the UK is protective for LO despite a significantly higher rate of diabetes in the UK. A larger study is warranted based on these preliminary findings.