Smart had missed the Celtics' previous eight games with a case of viral conjunctivitis, an infection that affected both of his eyes.
"I thought I was going to go blind for a while," Smart said prior to missing the team's Christmas Day game at the Raptors. "I think it was the worst case of viral conjunctivitis that they've seen.
"It was the worst pain that I've been through in a very long time. I don't wish it on anybody."
The last time Smart played was Dec. 6 against the Denver Nuggets. He said the combination of getting an allergic reaction and a really bad cold in the wake of that game broke down his immune system -- and set the stage for him to be knocked flat by this virus.
Smart is averaging 11.8 points, 3.4 rebounds and 4.6 assists in 20 games this season.