Valeant Pharmaceuticals International said today that it has raised its bid for Irvine-based eye drug maker Ista Pharmaceuticals Inc.

Ista shares were up 13% in midday New York trading to a market value of about $342 million.

Canadian-based Valeant said that its new offer values Ista at $360 million, or $7.50 a share, and could possibly raise that to $8.50 a share based on a review of Ista’s operations. Valeant said its offer expires Jan. 31.

Ista said it would consider Valeant’s offer as part of an ongoing review of strategic options. Ista also said it is “in dialogue with a number of parties that have expressed an interest in pursuing a strategic transaction.”

The drug maker views Valeant’s “willingness to raise its bid at least $2 per share as a clear indication of the inadequacy of its initial proposal,” Chief Executive Vicente Anido Jr. told the Associated Press.

Valeant revealed in December that it had made a $314 million offer to buy Ista. Ista rejected that bid, saying it was not in the best interest of its shareholders and that it was too low.

Today’s offer is a 93% premium from what Ista was trading at on Dec. 15, a day before the Valeant bid became public.

See this week’s Business Journal for additional coverage of the Ista-Valeant story.