We examined 50 patients to determine whether differences exist between the initial clinical signs and symptoms associated with infected vs sterile corneal infiltrates. A detailed history regarding contact lens use and ocular symptoms was taken, after which a careful slit-lamp examination was performed. The ocular findings were correlated with the results of corneal cultures. Increased pain (P less than .001), discharge (P less than .0001), epithelial staining (P less than .0001), and anterior chamber reaction (P less than .0001) were associated with infected ulcers. Sterile infiltrates were usually smaller; multiple or arcuate; and without significant pain, epithelial staining, or anterior chamber reaction.