Staal was hurt during the third period of Tuesday's 4-2 win over the Philadelphia Flyers when he was hit in the right eye by puck off a deflected slap shot launched by defenseman Kimmo Timonen.
He immediately fell to the ice, writhing in pain while holding a hand over his eye.
The Rangers said an examination performed Wednesday by an ophthalmologist and a maxillofacial surgeon revealed Staal's condition had improved, with the doctors expressing optimism he will make a full recovery.
Staal does not wear a visor and the incident has re-ignited a debate on whether such face shields should be mandatory in the NHL, as they are in most other levels of organized hockey.
The players' union is opposed to mandating their use, but the league is pushing for a rule requiring visors.
"The league continues to support a rule that would make visors mandatory in NHL games," Deputy Commissioner Bill Daly said in an email to The New York Times.