Royals catcher Salvador Perez goes on the illjured list due to eye pressure causing poor vision:

The Royals placed Perez, the team’s hottest hitter and a five-time Gold Glove award winner, on the IL with fluid buildup in his left eye, or a central serous chorioretinopathy. The move is retroactive to Aug. 18. 

KansasCity.com

The good news is doctors expect the condition to clear up.