Zach Smith scored for the Senators with 13 seconds left in the middle period and New York tied it on Matt Martin's goal 5:27 into the third.
The Islanders stopped a two-game skid while the Senators have lost five in a row. It was Ottawa's first appearance at home following a six-game road trip.
Evgeni Nabokov made 23 saves for the Islanders. Anderson stopped 30 shots.
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