1570
The author postulates that in cases of ethambutol associated chiasmopathy , ethambutol may initially affect the optic nerves and subsequently progress to involve the optic chiasm .
 Chemical: ethambutol; Chemical: ethambutol
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: ethambutol; Chemical: ethambutol