It had long been suspected that presbyopia, an age-related reduction in the ability of the eye to see clearly at near distances, had the potential to limit the productivity of adult workers who rely on vision to perform task at near. Before 2018 there were no randomised controlled trials demonstrating the link between near vision and workplace productivity. Earlier studies contained no control groups, and the outcome assessed were not precisely defined.
PROSPER (PROductivity Study of Presbyopia Elimination in Rural-dwellers) was the first randomised controlled trial to demonstrate a significant increase in relative productivity of more than 20% among intervention-group members in this rural cohort of mostly female participants, with a low-cost and widely accepted intervention of near glasses for correction of presbyopia. PROSPER I was an investigator-masked, randomised trial carried out in Assam, India. 751 consenting adults were randomly assigned to either the intervention group or control group. People in the intervention group received reading glasses at the beginning of the trial. People in the control group will receive free glasses at the end of the trial if they need them.
Workers aged 40–44 years who received glasses harvested 15·8% more than those who did not wear glasses. Similarly, workers 45–49 and 50 years or older who received glasses harvested 18·9% and 31·6% more, respectively, than those who did not wear glasses.
PROSPER I demonstrated that adult presbyopic agricultural workers benefit from eye examinations and vision correction, and that these gains increased with increasing age.
ClinicalTrials.gov Identifier: NCT03228199