A professor of physics at Oxford University, Silver was idly discussing optical lenses with a colleague, wondering whether they might be adjusted without the need for expensive specialist equipment, when the lightbulb of inspiration first flickered above his head.
What if it were possible, he thought, to make a pair of glasses which, instead of requiring an optician, could be "tuned" by the wearer to correct his or her own vision? Might it be possible to bring affordable spectacles to millions who would never otherwise have them?
More than two decades after posing that question, Silver now feels he has the answer. The British inventor has embarked on a quest that is breathtakingly ambitious, but which he insists is achievable - to offer glasses to a billion of the world's poorest people by 2020.
Some 30,000 pairs of his spectacles have already been distributed in 15 countries, but to Silver that is very small beer. Within the next year the now-retired professor and his team plan to launch a trial in India which will, they hope, distribute 1 million pairs of glasses.
Silver has devised a pair of glasses which rely on the principle that the fatter a lens the more powerful it becomes. Inside the device's tough plastic lenses are two clear circular sacs filled with fluid, each of which is connected to a small syringe attached to either arm of the spectacles.
The wearer adjusts a dial on the syringe to add or reduce amount of fluid in the membrane, thus changing the power of the lens. When the wearer is happy with the strength of each lens the membrane is sealed by twisting a small screw, and the syringes removed. The principle is so simple, the team has discovered, that with very little guidance people are perfectly capable of creating glasses to their own prescription.
"The reaction is universal," says Major Kevin White, formerly of the US military's humanitarian programme, who organised the distribution of thousands of pairs around the world after discovering Silver's glasses on Google. "People put them on, and smile. They all say, 'Look, I can read those tiny little letters.'"
Making and distributing a billion pairs of spectacles is no small task, of course - even at a dollar each (the target cost), and without Silver taking any profit, the cost is eye-watering.
This is what Silver calls "the challenge of scaling up".
"Work is going on on several new designs, and further work will be required to get the costs down. The truth is that there is, at the moment, no device that can be made for a dollar in volumes of 100 million.
"But I am entirely confident that we can do that."
Such is his determination, you wouldn't bet against it. Oxford University, at his instigation, has agreed to host a Centre for Vision in the Developing World, which is about to begin working on a World Bank-funded project with scientists from the US, China, Hong Kong and South Africa. "Things are never simple. But I will solve this problem if I can. And I won't really let people stand in my way."