In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: The dexamethasone - treated nonresponder eyes appeared to be morphologically similar to the untreated eyes , although several subtle dexamethasone - induced morphologic changes were evident .
### Output Text:
The <span class="chemical">dexamethasone</span> - treated nonresponder eyes appeared to be morphologically similar to the untreated eyes , although several subtle <span class="chemical">dexamethasone</span> - induced morphologic changes were evident . 