PLOS ONE published an RCT of a program providing free reading glasses to adults needing near-vision correction in Bangladesh (where ~1/3 of adults need such correction but only 3% get it). Quick take: High-quality RCT finds sizable 33% gain in workforce earnings at 8-month mark.
Program and Study Design:
The study sample comprised 824 adults age 35-65 screened as needed reading glasses, half of whom were in jobs involving near-vision activities (e.g., tailor, mechanic, farmer, artisan). They hailed from 59 villages, and constituted 8% of all adults age 35-65 in their villages.
The sample was randomized to treatment (glasses provided by trained non-medical personnel) vs control (who received glasses 8 months later).
Based on careful review, this was a well-conducted RCT (e.g., baseline balance, prespecified outcome, low attrition, blinded assessors).
Findings:
At the 8 month mark, the study found a statistically significant 33% gain in past-month earnings (US$47 treatment vs $35 control).
Comment:
I believe the findings may be of great policy importance: Bangladesh's 3% rate of adult reading vision correction is typical of many low-income countries. So this straightforward, low-cost intervention could potentially bring sizable earnings gains to millions worldwide.
But first, a replication RCT is needed - preferably in another country and with longer-term follow-up - to hopefully (1) confirm the findings (i.e., rule out the possibility they're spurious) & (2) establish that the impacts generalize to other settings and ideally persist over time.