Baker didn't react when the Dodgers' Russell Martin lined a single past him to lead off the eighth inning. Cubs manager Lou Piniella went onto the field to talk to the infielder and then replaced him with Mike Fontenot.
"Baker had vision problems and couldn't see out of his right eye," Piniella said. "It was a little scary."
Baker was examined by Dr. Jon Rosin, the team opthamologist. The club expected to know more on Friday.
"We had to get him out of there," Piniella said of Baker.
Fontenot led off the Chicago eighth with a triple and scored the game-winning run on Tyler Colvin's double in the Cubs' victory.