Garland, 22, left the team and was checked Thursday at the Cleveland Clinic Cole Eye Institute. The Cavs said he'll be reevaluated over the next two days before his status is updated.
It's likely Garland will miss Cleveland's game in Chicago on Saturday. The Cavs host Washington in their home opener Sunday.
Cavs coach J.B. Bickerstaff saw Garland before he left the team, which practiced in Canada before flying to Chicago.
"It does not look pretty," Bickerstaff said of Garland's injured eye. "When you take a hit right in that inner part of the eyelid and the eye, it's swollen and then bloodshot on the eyeball. Just hope he gets better."
After being poked, Garland dropped to the floor and was down for several minutes before being helped up and walking slowly to the locker room. Without Garland for three quarters, the Cavs lost 108-105.
Garland scored four points and had three assists in 13 minutes before getting hurt. It was his first game playing with All-Star Donovan Mitchell, acquired in a trade from Utah during the offseason.
Bickerstaff said he was not aware of Garland having any problems with his vision.
"But the eye is shut," he said. "It's hard to see when your eye is closed. But when he is able to hold his eye open, he can see at this point."
If Garland is out for a few games, Bickerstaff, who spent most of last season dealing with injuries, will have to shuffle his starting lineup. Bickerstaff has plenty of options, including veteran backup Raul Neto, and his decision will likely be determined by how the Cavs match up with their opponent.
Garland blossomed into one of the NBA's best point guards last season, averaging 21.7 points and 8.6 assists while helping the Cavs win 22 more games than they did the previous year. He was chosen as an All-Star for the first time, and Cleveland signed him to a five-year, $193 million contract extension in July.