"My eyes have been fluttering on me for the last couple of weeks, and it finally caught me during a game," Damon said. "I definitely don't want that to happen again. We'll see why there's some twitch in there."
Damon initially downplayed the issue, wondering aloud if he is suffering from allergies. But his thoughts turned more serious as he pondered that it could be an after-effect of his 2003 collision with infielder Damian Jackson while with the Red Sox.
Damon said that he felt dizzy after he dropped David Ortiz's fly ball in the fourth inning of a 4-3 loss to the Red Sox on Thursday in Boston.
"I almost felt like I passed out for a second," Damon said. "That's another thing I want to check out -- to make sure that after the concussion from three years ago, there's no lingering effects from that."
Yankees manager Joe Girardi said the club was not aware of the issue until after Damon dropped Ortiz's fly ball.
"He said his eyes have basically not been normal the last couple of weeks," Girardi said. "Yesterday was the first time he brought it to our attention, though."
Damon mentioned the "fluttering" in a postgame interview with reporters on Thursday but did not offer as many details as he did on Friday. Damon said he has had trouble seeing the ball and was relying on outfielders Melky Cabrera and Brett Gardner for guidance on Thursday.
"It's very embarrassing as a ballplayer when you can't catch a simple fly ball," Damon said. "Every time I looked up to try to catch a fly ball, it wasn't there. I was relying on Melky and Gardner yesterday on those balls. It seemed like I couldn't focus in on anything."
Damon said that he "had pitches I could have crushed" during the series at Fenway Park, leading to his 1-for-13 series, but the No. 2 hitter in the Yankees' lineup vowed he would be ready to play Friday if needed off the bench.
Cabrera started in left field for the Yankees on Friday, while Gardner got the start in center field and Nick Swisher started in right.
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.