Kiermaier left Saturday night's game against Toronto in the fifth inning after first experiencing discomfort while shagging balls during batting practice.
"A couple minutes in, I was like, dang it, I got an eyelash in my eye," Kiermaier said. "There was an eyelash in there and then we rinsed my eye, and then it disappeared or kind of went into one of these crevices or whatever. Once that happened, everything took a turn for the worse."
"I don't know how or if we scratched, that's definitely what it feels like," Kiermaier added. "I keep telling people it just feels like a piece of sand on the inside of my eyelid. Every time I blink, just pressure, irritation, a scratching feeling."
Kiermaier did not start in Sunday's 6-4 victory over the Blue Jays, but Tampa Bay manager Kevin Cash did insert him in center field in the bottom of the ninth inning. He did not get an at-bat.
He returned to the starting lineup on Monday, playing center field and going 0-for-5 in the Rays' 14-8 extra-innings victory, their 11th straight.
On Sunday, Kiermaier had said he felt slight improvement.
"Still feel a little bit of a scratch or irritation, whatever we've got going on in there," he said.
Kiermaier has a history of offbeat injuries, including hurting his hand during a base-running slide and injuring a wrist while attempting a diving catch.
"It's just one of those weird things," he said. "Seems like this stuff could only happen to me. Got to get through it and roll with the punches. I'll be fine. I assume I'll be 100% whenever my eye chooses to cooperate, but we're kind of waiting for that moment."
The Associated Press contributed to this report.