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: RESULTS : A significant increase in intraocular pressure developed in 13 of the 44 pairs of eyes perfused with dexamethasone with an average pressure rise of 17 . 5 + / - 3 . 8 mm Hg after 12 days of dexamethasone exposure .
### Output Text:
RESULTS : A significant increase in intraocular pressure developed in 13 of the 44 pairs of eyes perfused with <span class="chemical">dexamethasone</span> with an average pressure rise of 17 . 5 + / - 3 . 8 mm Hg after 12 days of <span class="chemical">dexamethasone</span> exposure . 