New evidence has suggested that a pair of spectacles can improve workers’ productivity and reduce poverty.

Sponsored by global sight campaign Clearly, a trial conducted with 750 mainly female Indian tea pickers has shown that after being provided with glasses, their productivity improved by 21.7% as those wearing glasses picked over five kilos daily more than before.

The increase was 31.6% with those aged over 50. The country’s crop industry could gain an extra $19m in growth from this extra productivity, researchers said.

The findings from a study called Prosper and published in The Lancet Global Health should intensify the pressure on companies to make sure that their workers have access to glasses and eyecare treatments.