"I just woke up this morning and it was just blurry in my left eye," Prado said. "I drank a lot of water, put a lot of drops in there, but it didn't work out well."
Prado softly lined out in the second inning and grounded out to end the third.
"I wasn't recognizing [any pitches]," Prado said. "It wasn't a good idea to keep playing like that."
When the D-backs took the field for the fourth inning, Eric Chavez took Prado's place at third base.
The move ended up working out for the D-backs, as Chavez hit a two-run homer in the fifth inning to put Arizona up, 5-3.
"I tried, but if I'm not 100 percent, I wouldn't take the chance of playing the whole game," Prado said. "It was fortunate for the team because Chavy had a great at-bat and hit a homer that helped the team to win a game."
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.