In 1999, Martínez was diagnosed with strabismus, a condition which causes the eyes to not properly align. For Martínez, his right eye would intermittently drift and cause him to lose depth perception. For the 1999 season, he led the AL with a .447 OBP and batted .337. He recorded his 1,500th hit on August 14. In 2000, Martínez earned his fifth All-Star Game selection. He hit 37 home runs, his single-season best, and led the American League with 145 RBIs. The Mariners reached the postseason, and Martínez batted .364 in the 2000 ALDS, defeating the Chicago White Sox. The Mariners lost to the Yankees in the 2000 American League Championship Series (ALCS). Martínez finished sixth in AL MVP Award balloting, and won the Outstanding Designated Hitter Award.