The Aquamarine Festival was held near the town of Vladimir, around 170 km (106 miles) east of Moscow on July 5. People started seeking medical assistance on July 7, complaining of aching eyes and eyesight loss.
"Usually, laser beams at such concerts are directed into the air. But it was raining heavily and the organizers had to stretch a canopy over the dance floor, and the [laser] beam at times fell below the canopy," one of the victims was quoted by Kommersant as saying.
A doctor told Kommersant that many of the victims, aged between 16 and 30, who sought medical treatment were suffering from burnt retinas.
Doctors say the "loss of eyesight is up to 80% in some cases" and for some of the victims "it will not be possible" to restore their eyesight.
Those affected by the laser have made complaints against the organizers. "The doctors must prove, that the injuries were caused only by the laser, and not by alcohol or, for instance, loud noise," one of the patients said, however.
Cosmic Connection, the concert organizer and promoter has been unavailable for comment.
The head of the EQ laser show firm, Valentin Vasilyev, however, called the incident "unprecedented" and told Kommersant that if a laser beam hit the retina, then the burn would be instantaneous and blamed poorly trained personnel and badly maintained equipment for such incidents.
But a DJ involved in music festivals said the firm that organized the concert had all the required health and safety certificates.
