Reading Glasses Boost Garment Worker Productivity in India: British Journal Study

The PROSPER II Study: A Breakthrough in Vision Correction for Garment Workers

A groundbreaking randomized controlled trial known as PROSPER II has demonstrated that providing simple reading glasses to garment factory workers in India can significantly enhance their productivity. Published in the prestigious British Journal of Ophthalmology on April 27, 2026, the study focused on correcting presbyopia, an age-related condition that impairs near vision, among sewing machine operators. Presbyopia (from Greek 'presbys' meaning old man and 'ops' meaning eye) typically begins around age 40, making close-up tasks like threading needles or inspecting seams challenging without correction.

Conducted in factories owned by Shahi Exports, India's largest apparel manufacturer employing over 100,000 people, the trial enrolled 682 workers with a mean age of 41 years, 99% of whom were women. Participants were randomized into two groups: 344 received free near-vision glasses immediately, while 338 served as controls receiving them after 12 weeks. All completed the study period, ensuring robust data collection on real-world factory performance.

Understanding Presbyopia in the Context of India's Garment Sector

India's garment industry is a cornerstone of the economy, contributing significantly to exports and employing millions, particularly women. Tamil Nadu alone accounts for 43% of India's 1.6 million women factory workers, with hubs like Tirupur and Bangalore leading production. The sector faces intense global competition, slim margins, and labor-intensive processes where precision near vision is crucial. Uncorrected presbyopia affects an estimated 177 million Indians, with prevalence rising sharply over 40—up to 43% in some rural adult populations aged 30+.

In garment factories, 27% of sewing machine operators suffer from uncorrected near vision impairment, leading to slower output, more errors, and potential job loss as workers age. This not only impacts individual livelihoods but also hampers industry efficiency in a sector projected to grow amid rising apparel demand.

Methodology: Rigorous Design for Factory Floor Reality

The PROSPER II trial, registered as NCT04629820, was investigator-masked and multi-center, screening 4,990 workers across Shahi Exports facilities in Karnataka. Eligibility required age 35+, uncorrected presbyopia (near visual acuity worse than 6/12), and active employment as sewing operators. Exclusion criteria included other eye diseases or glasses ownership.

• Vision screening using standardized charts and autorefraction.
• Ready-made reading glasses dispensed on-site (+1.00 to +2.50D).
• Primary outcome: normalized hourly garment pieces completed, tracked via factory piece-rate systems over 12 weeks.
• Secondary: error rates, visual function questionnaires, adherence (monitored weekly).

Analysis used adjusted panel regression accounting for skill grade (A-C), machine type, and baseline factors, ensuring statistical power to detect 8% productivity difference.

Key Results: Quantifiable Gains in Output and Quality

The intervention group outperformed controls by 5.70% in productivity (95% CI 1.04% to 10.4%; p=0.017; absolute difference 0.0325 normalized units). Lower-skill grade C workers benefited most, highlighting equity impacts. Errors decreased, and output quality improved, with visual function scores rising significantly (mean difference -15.4; p<0.001).

Adherence improved from 41% at 4 weeks to 65% at 12 weeks, supported by training. Per-worker annual benefit: US$162, far exceeding the <$10 intervention cost. Over 12 weeks, return on investment reached 337%, projected to 1,600% annually if sustained.

Economic Implications: Billions in Potential Value

For Shahi Exports, scaling to 100,000 workers could yield massive gains. Globally, applying to textile/garment sectors in low-income countries might add $27 billion in annual output—equivalent to 3.8 billion extra garments. In India, where apparel employs 45 million (formal and informal), even partial uptake could boost GDP.Full PROSPER II paper (BJO)

"This research tells us that through a simple pair of eyeglasses we are investing both in the wellbeing of our workers and in the productivity of our business," said Anant Ahuja, Director of ESG at Shahi Exports. Partners like VF Corporation and Primark are expanding screenings.

Building on Prior Evidence: From Tea Gardens to Factories

PROSPER I (2018, Lancet Global Health) showed 22% productivity rise for Indian tea pickers over 50. Bangladesh garment studies reported 33% income gains for women. Earlier South African textile research noted 6.4% boosts. PROSPER II confirms manufacturing benefits, closing evidence gaps.PROSPER I trial (Lancet)

• Tea pickers: +21.7% overall, +32% >50 years.
• Bangladesh crafts: Income +33%.
• Global meta: Consistent near-vision gains across manual jobs.

Challenges in India's Garment Workforce

Women dominate (80-90% sewing roles), facing long hours, poor lighting, and limited healthcare access. Aging workforce (average 35-45) exacerbates presbyopia. Barriers include glasses cost (Rs 200-500), stigma, and supply chain gaps in rural clusters like Tirupur.

Prevalence studies: 20-23% near impairment in young garment workers (30-34), rising to 54% overall refractive issues.

Solutions and Scaling Initiatives

Shahi's commitment to screen all 100k workers sets precedent. VisionSpring's model—on-site screening, ready-made glasses—costs low, uptake high. Government schemes like Ayushman Bharat could integrate vision. NGOs and brands (H&M, Gap) partner for CSR.

Policy recommendations: Mandate vision checks in factories, subsidize glasses via PLI scheme for apparel. Training boosts adherence.

Photo by Vikas Makwana on Unsplash

Future Outlook and Research Directions

Long-term studies needed on retention, wage impacts, multi-year ROI. Integrate with digital tools for adherence tracking. Broader LMIC application via WHO VISION 2020. In India, potential to lift millions from poverty, aligning with Viksit Bharat.

Stakeholders—unions, employers, policymakers—must prioritize. Simple intervention unlocks human potential in labor heartlands.