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: With these findings in rats , it is hypothesized that the temporary diplopia sometimes seen in patients after ophthalmic surgery might be due to anesthetic - induced damage to the extraocular muscles .
### Output Text:
With these findings in rats , it is hypothesized that the temporary diplopia sometimes seen in patients after ophthalmic surgery might be due to anesthetic - induced damage to the extraocular muscles . 