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: Bilateral retinal artery and choriocapillaris occlusion following the injection of long - acting corticosteroid suspensions in combination with other drugs : I .
### Output Text:
Bilateral retinal artery and choriocapillaris occlusion following the injection of long - acting <span class="chemical">corticosteroid</span> suspensions in combination with other drugs : I . 