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: Ophthalmological assessment revealed features of chloroquine retinopathy , cardiac assessment revealed features of heart failure and a complete heart block with right bundle branch block pattern .
### Output Text:
Ophthalmological assessment revealed features of <span class="chemical">chloroquine</span> retinopathy , cardiac assessment revealed features of heart failure and a complete heart block with right bundle branch block pattern . 