Barzal had a procedure done on his kneecap Thursday and is expected to miss about six weeks, Pierre LeBrun of TSN reports Saturday.
Barzal (lower body) was placed on injured reserve Tuesday.
Barzal (lower body) is out indefinitely, the Islanders announced Monday.
Barzal (undisclosed) will miss Sunday's game against Florida, per Stefen Rosner of NHL.com.
Barzal notched two assists, including one on the power play, and three shots on goal in Monday's 3-1 win over the Blue Jackets.
Barzal registered a goal on three shots, an assist and a plus-2 rating in Saturday's 4-1 win over the Sharks.
Barzal scored a goal on two shots in Thursday's 5-3 loss to the Flyers.
Barzal scored an empty-net goal on five shots and went plus-2 in Saturday's 6-3 win over the Maple Leafs.
Barzal (upper body) was activated from long-term injured reserve Sunday, per the NHL media site.
Barzal (upper body) will be a game-time decision for Sunday's game against Chicago, Stefen Rosner of NHL.com reports.