Revellers at an outdoor rave in Moscow were nursing more than hangovers this week when the laser show that accompanied music at the festival started blinding them.
The light show was at Aquamarine Open Air Festival in Kirzhac, near Moscow. So far 29 people have been taken to hospital, with what is severe scarring on their retinas.
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The laser damage is said to have happened because of the use of outdoor lasers indoors.
Torrential rain meant that the open air festival wasn't actually open air, but in a tent. The reflection of the lasers in the tent hit the crowd instead of the sky and damaged many of the partygoers' vision.