The Bolshoi ballet's artistic director Sergei Filin was convalescing in Moscow on Saturday following an acid attack to his face, but doctors said they would need at least a week to know how much vision he will retain. A masked man cornered Filin near his house late Thursday and threw acid on his face. Following emergency surgery on his eyes, the former dancer was taken out of intensive care and was in stable condition in a regular hospital room, Alexander Mitichkin, the head doctor at Moscow's Clinic 36 told Russian news agencies Saturday. Police declined to discuss any leads in the case or the type of acid used in the attack, despite top officials on Friday saying the probe was a top priority. Investigators were questioning Filin in hospital, a Moscow police spokesman told Interfax. Filin's eyes will remain bandaged for days, and it was unclear how much eyesight, if any, the ballet chief would regain. He will also have to undergo cosmetic surgery procedures after the third-degree burns to his face. Initial plans to move Filin to a top burns hospital near Brussels were scrapped after it was decided that saving his eyes was a higher priority, Bolshoi spokeswoman Katerina Novikova said in televised remarks. The attack on Filin, a charismatic 42-year-old who was appointed to the Bolshoi in 2011 and began adding modern stagings to the theatre's classic repertoire, horrified the dance community and stirred rumours around the institution, revered in Russia but periodically enveloped in scandals. Filin's colleagues and Bolshoi's general director Anatoly Iksanov said Filin's professional work was the reason for the attack, and that it was the finale of a long-term intimidation campaign which included hack attacks to his website, phone calls, and damage to his car. The Vesti channel on Saturday said the colleagues had a suspect in mind, but weren't sharing the identity with the media. In a sign that other energetic culture figures may be under similar pressure, another artistic director, Kirill Serebrennikov of Moscow's Gogol drama theatre said he has also been intimidated by unknown individuals. After Filin's attack, Serebrennikov posted on Facebook a threatening text message he received on New Year's Eve. "If you don't leave the Gogol Theatre, then you are next," the message said. "You will be beaten for real, you just wait." "I've received threats for a long time," wrote Serebrennikov, an award-winning film and theatre director who was appointed to revamp the old-fashioned Gogol theatre last summer amid protests from the troupe.