A laser show at a Russian techno festival last weekend resulted in more than 30 revellers being left partially blinded.When organisers placed a reflective tarpaulin over the stage at one of the arenas, lasers were reflected into the crowd.

Since the Aquamarine Festival in Vladimir, 170km east of the city, scores of ravers have been checking into Moscow hospitals with burnt and scarred retinas.

'You can see scars on them,' one doctor told local newspaper Kommersant. 'The loss of eyesight in some cases is up to 80 per cent and it's unlikely it can ever be restored.'