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: CONCLUSION : Dexamethasone treatment of isolated , perfusion - cultured human eyes led to the generation of ocular hypertension in approximately 30 % of the dexamethasone - treated eyes .
### Output Text:
CONCLUSION : <span class="chemical">Dexamethasone</span> treatment of isolated , perfusion - cultured human eyes led to the generation of ocular hypertension in approximately 30 % of the <span class="chemical">dexamethasone</span> - treated eyes . 