A simple pair of eyeglasses increases earnings and productivity for tea pickers in India

SAN FRANCISCO — It is the high season in Assam, a state in Northeastern India, and from June to October the amount of tea picked is limited to what the women working in the fields can harvest by hand, rather than the rate of plant growth. Here, income is directly tied to productivity.

Women walk through rows of green plants, pluck each leaf and bud they can see, and toss them into baskets on their backs. When they return and weigh the leaves, only then do they learn what they will make for a long day of work.

Those tea pickers are at the center of a new study demonstrating the outsized impact that improved eyesight can have on productivity and income. A trial of 751 Indian women tea pickers over the age of 40, demonstrated that the provision of glasses improved their productivity by 21.7 percent, and by 31.6 percent for those over age 50. The results of the randomized controlled trial, or RCT, conducted at three tea estates in Assam and published Tuesday in The Lancet Global Health, point to the impact that eyeglasses can have on worker productivity.

These results surpass the productivity increases reported by every other health intervention in low- and middle-income countries studied in scientific literature trials.

The team behind the study explains the role eyeglasses could play in achieving the Sustainable Development Goals, as 2.5 billion people with poor vision lack access to glasses, making it the largest unaddressed disability in the world.

“Seven-hundred years after glasses were first invented we now have conclusive proof of the link between clear vision and productivity. Poor vision is the scandal the world forgot and affects a third of the world’s population. Solving this issue will accelerate progress against the U.N.’s goals on health, quality education, decent work, gender equality, and poverty elimination,” James Chen, founder of Clearly, a global campaign to bring clear vision to those who lack it and the study sponsor, said in a press release.

The study is called PROSPER, also known as the Productivity Study of Presbyopia Elimination in Rural-dwellers — Presbyopia is farsightedness that typically begins in middle and old age. Published at the same time as the first ever Global Disability Summit in the United Kingdom, this is the first trial to demonstrate a link between clear vision and work performance. The research was carried out by VisionSpring, a social enterprise that sells affordable eyeglasses in developing countries, and Orbis International, an international NGO focused on fighting avoidable blindness.

The trial was carried out over three months in tea estates in Assam, India. Women who were given glasses had a nearly 5-kilogram increase — from 26 kg to 30.6 kg — in the daily weight of tea picked, which translated into increased earnings. The benefits weren’t just on an individual level — if the intervention were replicated across India’s crop industry, it would mean an extra $19 billion in productivity gains, according to the groups behind the study. And as productivity increased in the group wearing glasses, it decreased in the control group, indicating how the effects uncorrected presbyopia have on productivity get worse with age.

In 2015, less than 1 percent of global health resources, or $37 million, were spent on delivering eyeglasses to people in developing countries, according to EYElliance, a multistakeholder coalition started by the founder of VisionSpring that is working to bring attention to the problem of untreated vision problems, which cost the global economy $200 billion annually in lost productivity.

“Vision changes lives,” said Nathan Congdon, professor at Queen’s University Belfast and the principal investigator of the Lancet study. “Having good vision makes a huge difference in people’s lives, whether its education, the ability to make enough money to feed your family, getting home safely from work.”

The women in the study had never seen a pair of glasses, he said, and initially, they feared they would look silly. But when people realize they can do their job more effectively and make more money with corrected vision, they keep wearing the glasses.

Nearly 90 percent of workers were still wearing their glasses by the end of the study, and 95 percent said they were willing to pay for them if they were lost or broken.

Congdon said he thinks these results are exciting for donors because eyeglasses are an intervention that sell themselves. Still, a number of systemic issues stand in the way. For example, in parts of rural India, glasses are seen as a sign of sickness, and even in places where people want glasses, there are rarely enough eye doctors or clinics.

The study may intensify pressure, not just on donors, but also on companies to ensure that their workers have access to free work-based sight tests, eyeglasses — which can cost as little as $1.50 — and other eye care treatments. Clearly plans to share the results with leading businesses, to encourage them to introduce these types of programs.

Indeed, the owner of the tea garden where the trial took place said the study made the case for providing sight tests and improving vision for business employees.

“At the heart of this study there is a clear message for businesses like ours — good vision is vital to what we do,” said Conrad Dennis of Amalgamated Plantations Private Limited. “This is a turning point in awareness of the impact of clear vision on our tea garden’s well-being and productivity.”

“The evidence shows definitively that eyeglasses are a powerful social and economic development tool,” Ella Gudwin, president of VisionSpring, told Devex via email. “And vision screening for workers offers an easy to implement, high-impact way to boost the income of lower-income workers as well as business performance.”

Gudwin said she hopes the results will help to encourage large-scale partnerships and collaborative efforts with employers, buyers, industry coalitions, government agencies, philanthropists, and investors who can now see the benefits for families, businesses, and local economies.

“We now know definitively that a simple pair of reading glasses transforms workers’ productivity, not just in offices but in agriculture,” she said.

“This has profound implications. It means there is a cost-effective and easy way to boost both household income and business performance in lower-income communities. While the study focused on tea estates, we see broad applicability across a wide range of labor-intensive workplaces.”

That might include apparel, coffee, home goods, or any other production processes that require clear vision at near distances.

“A handful of studies have looked at the question about what the impact is of uncorrected presbyopia on day to day things we might do, and those studies have shown the ability to recognize money, to read and write, to use a smartphone, to weed a garden, to sew and use a needle and thread effectively — all of those things appear to be less in people who don’t have glasses,” Congdon told Devex.

It might be hard to distinguish the impact from the loss of ability to focus on nearby objects, from a range of conditions that come with old age, such as arthritis. So there was a need for evidence that correcting presbyopia makes a difference in terms of productivity resulting from a controlled study, Congdon said.

The authors of the study say they hope to see additional trials with different groups in other geographies. Meanwhile, other studies are already in the works, including one on the textile industry in Bangladesh, Congdon added.

There is also a need for more operational research designed to figure out the best and most efficient ways to distribute eyeglasses in low-resource settings, Congdon explained. He noted that in many countries where there are few optometrists it is illegal for someone without a medical background to sell glasses, even for near vision correction, a future trial might determine whether there is any rationale for that.

Clearly will continue to fund RCTs to uncover the links between better eyesight and productivity, education, and driver safety — all essential to achieving the SDGs, said Graeme MacKenzie, head of research.

Even Clearly was stunned by the scale of the results, MacKenzie said. Now, the challenge is, not only to fund more research, “since replication of scientific results is essential to good science,” but also to ensure that governments and businesses offer sight tests and affordable glasses for all.

There’s not enough awareness on the importance of glasses to achieve the SDGs, he said, and he sees PROSPER as an important first step in providing groups with the evidence they need to prioritize universal access to vision services.

“We’re researchers. We like to publish. But publication is really just the first step,” he said. “We feel this study can generate this kind of enthusiasm needed to get a lot of companies and NGOs together to make this happen and make workplace distribution of these glasses a reality all around the world.”

Now, a year out from the study, the same researchers are going back to make sure the women are still wearing the glasses. Their work will focus on qualitative research and focus groups with the women. They want to see what benefits the eyeglasses provide beyond the tea fields.