Doctors said Sergei Filin, the director of ballet at Moscow’s Bolshoi Theatre, was in “stable” condition on Saturday, after suffering severe burns to his eyes from an acid attack.

“His condition is stable, and he is no longer in the ICU,” said Alexander Mititschkin, the head doctor at Moscow’s Clinic 36, according to the Interfax news agency.

Mr. Filin underwent emergency surgery on Friday to save his eyesight, but Mr. Mititschkin said it will take several weeks before doctors know how much vision he could eventually regain.

The 42-year-old, who has run the world’s biggest and most prestigious ballet company since 2011, suffered serious injury to his eyes and the skin of his head after a masked man threw acid in his face outside his home late Thursday.

He is expected to undergo further procedures to treat the burns on his face.

Investigators have yet to name a suspect or comment on the motive behind the attack, but friends have speculated it may stem from resentments over power or casting decision at the Bolshoi.

Deputy Prime Minister Olga Golodets has personally assumed responsibility for the case, Russian media reported.

Mr. Filin, who is married with children, was one of the world’s top male dancers, famed for performing the role of the handsome prince in classics such as The Nutcracker, The Sleeping Beauty and Swan Lake.