Up to 30 partygoers at an outdoor rave have been partially blinded by a laser light show.

Health officials confirmed 12 cases of laser-blindness from the event, with reports suggesting up to 17 more.

Some of those affected have lost up to 80 per cent of their vision.

Guests at the Aquamarine Open Air Festival in Kirzhach, Russia, began seeking medical help days after the show, complaining of vision problems.

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Lasers like these were erected inside giant tents at the Aquamarine Open Air Festival in Kirzhach, Russia, after heavy rain. Up to 30 ravers suffered permanent damage to their vision.

Heavy rain had forced organisers of the event, which took place on July 5 in the town 50 miles outside Moscow, to put up tents for the all-night dance party.

The lasers, which are designed to illuminate the sky, were reflected by the canopy into the eyes of the ravers, burning their retinas.

An eye expert who treated some of the cases said the chance of regaining vision is 'already impossible'.

One partygoer said: 'I immediately had a spot like when you stare into the sun.

'After three days I decided to go to the hospital. They examined me, asked if I had been at Open Air and then put me straight in the hospital.

'I didn't even get to go home and get my stuff.'

Industry website www.laserfx.com said focused laser light such as that at the event can cause eye damage almost instantly.

The owner of one Moscow laser rental company blamed the blindings on 'illiteracy on the part of technicians'.

'It was partly the rain but also partly the size of the laser.

'Somebody set up an extremely powerful laser for such a small space,' said Valentin Vasiliev, whose company did not provide the lasers for the Aquamarine festival.

Cosmic Connection, which promoted the Aquamarine rave, was unavailable for comment.