Recently, a middle-aged woman came to see me in my ophthalmology clinic because her eyes felt gritty and uncomfortable. She had seen another doctor a month earlier who diagnosed her with eyelid inflammation and wrote her a prescription.

As I examined her eyes, she mentioned in passing the prescription medication she’d been using – ivermectin. This was the first I’d heard of this drug being used for itchy, uncomfortable eyes. I knew researchers had studied and rejected ivermectin as a cure for COVID-19, and that the medication is to treat onchocerciasis, a condition more commonly known as river blindness that is mostly seen in rural sub-Saharan Africa.

River blindness is caused by a parasitic worm that’s transmitted when people are bitten repeatedly by infected blackflies. A long neglected tropical disease, it’s mostly known for causing severe skin disfigurement and permanent blindness. So why was this patient with itchy eyes in the U.S. using the same drug used to kill a blinding parasitic worm?

This is just one instance where decades of investment and collaboration to fight a disease that affects the global poor had yielded an unexpected benefit – a treatment for eyelid inflammation, dry eyes and rosacea.

This medicine is just one data point in a pattern worth billions of dollars.

As a population health researcher, I see firsthand the benefits of investment in global health research. Global health research has a long history of producing treatments, knowledge and economic benefits that advantage wealthy countries in unexpected ways.

Economic investments paying........

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