The Bangladesh National Blindness and Low Vision Survey - Identification of prevalence, causes and the need for eye care services

Background: Bangladesh is a densely populated, impoverished country in South Asia with inadequate health service provision for a variety of diseases including treatable ocular conditions. The aims of this comprehensive research study were: a) to determine the prevalence and causes of blindness and low vision amongst persons aged 30 years and older, based on a nationally representative, randomly selected sample, b) to evaluate cataract surgical coverage and spectacle coverage for refractive errors, and c) to identify the socio-economic and cultural barriers to the uptake of eye care service provision amongst blind and visually impaired individuals. Methods: Multi-stage, cluster random sampling with probability-proportional-to-size procedures were used to select the sample of 12,782 adults age 30 years and older. Cluster site selection for the study was proportional to the rural/urban distribution of the national population. The examination protocol consisted of an interview, visual acuity (VA) testing, automated refractometry and optic disc examination on all subjects. Corrected VA re-testing, cataract grading, and a dilated fundal examination were performed on all visually impaired subjects. The definitions of blindness (<3/60) and low vision (<6/12 to ≥3/60) were based on the presenting visual acuity in the better eye. The World Health Organization/Prevention of Blindness proforma and its classification system for identifying the main cause of blindness and low vision for each visually impaired subject was used. Descriptive, univariate and multi-variable statistical analysis techniques, including binary logistic regression modelling, were carried out using Epi-Info and SPSS software. Results: In total, 11,624 adult subjects were examined (90.9% response rate) across the 154 cluster sites. An age-sex standardised prevalence of bilateral blindness of 1.53% was identified while a further 13.8% of subjects had low vision (