The effect on income of providing near vision correction to workers in Bangladesh: The THRIVE (Tradespeople and Hand-workers Rural Initiative for a Vision-enhanced Economy) randomized controlled trial

Abstract

Introduction Presbyopia, the leading cause of vision impairment globally, is common during working years. However, no trials have assessed presbyopia’s impact on income. Methods In April 2017, we conducted a census among 59 Bangladesh villages to identify persons aged 35 to 65 years with presbyopia (presenting distance vision > = 6/12 bilaterally and correctable inability to see 6/13 at 40 cm with both eyes), who never had owned glasses. Participants were randomized (1:1) to receive immediate free reading glasses (intervention) or glasses delivered 8 months later (control). Visual demand of different jobs was stratified into three levels. Outcomes were between-group differences in the 8 month change in: self-reported monthly income (primary) and Near Vision Related Quality of Life (NVRQOL, secondary). Results Among 10,884 census participants, 3,655 (33.6%) met vision criteria and 863 (23.6%) comprised a sample enriched for near vision-intensive jobs, but 39 (4.52%) could not be reached. All participants allocated to intervention (n = 423, 51.3%) and control (n = 401, 48.7%) received the appropriate intervention, and follow-up was available for 93.4% and 96.8% respectively. Groups were similar at baseline in all characteristics: mean age was 47 years, 50% were male, 35% literate, and about half engaged in "most near vision-intensive" occupations. Glasses wear at 8-month follow-up was 88.3% and 7.81% in intervention and control respectively. At baseline, both the intervention and control groups had a self-reported median monthly income of US$35.3. At endline, the median income for the intervention group was US$47.1 compared with US$35.3 for control, a difference of 33.4%. Predictors of greater income increase in multivariate models included intervention group allocation (OR 1.45, 95% CI 1.12, 1.88, P = 0.005), male sex (OR 2.41, 95% CI 1.84, 3.16, P <0.001), and not engaging in income-producing work at baseline (OR 2.35, 95% CI 1.69, 3.26, P<0.001). Conclusion Provision of reading glasses increases income in near vision-intensive occupations, and may facilitate return to work for those currently unemployed.