Scientists believe that some 4,000 years ago children as young as 10 wrecked their eyesight embellishing weapons and jewellery with minute scraps of gold, creating dazzling pieces so fine that the detail can barely be picked out with the naked eye. They were some of the best prehistoric metal work ever found in Britain.

The children may have been working in Brittany, where the largest concentration of daggers decorated with the tiny gold pins have been found, but the finest of all was excavated more than 200 years ago from a burial mound half a mile from Stonehenge.

Only fragments of the original wooden dagger handle survive intact, but originally it was decorated with 140,000 tiny studs, each almost as fine as a human hair and set into the wood at more than 1000 to the square centimetre. The price of such extraordinary work would have been painfully high, leaving some of the young craft workers very short sighted by the age of 15 and partially blind by the age of 20.

Ronald Rabbetts, an expert on the optics of the human eye, believes that only children and young teenagers would have had sharp enough eyesight for the most detailed work more than a thousand years before the invention of any form of magnifying glass.

It would quickly have damaged their sight, however, he believes, leaving them unfit for general work, but perhaps maintained by the tribe for the rest of their lives as specialist craft workers.

"Only children and teenagers, and those adults who had become myopic naturally or due to the nature of their work as children, would have been able to create and manufacture such tiny objects," he said. "There would almost certainly have been a section of the bronze age artisan class who, often as a result of their childhood work, were myopic for their adult life. They would therefore have been unable to do any other work apart from the making of tiny artefacts and would have had to be supported by the community at large."

The gold from the Bush Barrow burial mound, now on display in a new gallery at the Wiltshire Museum in Devizes, was already regarded as extraordinary – made using simple tools but with a sophisticated understanding of geometry and design. But this is the first time scientists have considered the human cost of such work. The results will be shown in a BBC2 documentary, Operation Stonehenge: What Lies Beneath on Thursday evening.

"Every time I've walked past the cases in our museum I've thought 'how the hell did they make them?' – and now we know," David Dawson, curator of the museum, said. "Our metal worker, Neil Burridge, who has made many replica pieces for us, has called them "the work of the gods" – but now we know they weren't gods but children."

In the programme the micro-artist Willard Wigan, whose tiny sculptures mounted in the eye of a needle or the head of a pin are avidly collected across the world, attempted to recreate some of the tiny studs, working under a microscope. "I cannot see an adult doing that because your eyesight starts to deteriorate even at 21," he said. "The quality of the work is phenenomenal."

The Bush Barrow burial mound was excavated in 1808, a period when there was a craze among amateur archaeologists for digging up the past. The skeleton, buried when the great stone circle was already 1,000 years old, was described by William Cunnington, a wool merchant who dug up scores of burial mounds with local land owner Sir Richard Colt Hoare, as the remains of "a stout and tall man". He was buried with one of the most spectacular collections of grave goods ever found in Britain, including an axe, a mace, a gold-belt plate, bronze and copper daggers, and an intricately decorated gold lozenge-shaped plaque on his chest.

The decayed wooden handle of one of the daggers had the most spectacular decoration, the tiny gold pins set so they overlapped like fish scales. Far more of it was intact when uncovered, but the ancient wood distintegrated: in a phrase to cause anguish to modern archaeologists, Cunnington described "a scatter of shining points of gold" as the excavator's trowel hit the handle.

Dawson said there was something heartbreaking as well as fascinating about the discovery. "It forces you to think of children working in conditions like child labour in carpet factories today ... the worst of it is they must have known it would ruin their eyesight, but still they persevered."