[header] How to diagnose and treat blepharitis in cats [title] Look for swelling of the eyelids. [step] When a cat has blepharitis its eyelids will likely swell due to the infection. Look for red and puffy eyelids in one or both of your cat's eyelids. 
[substeps] Because this infection is bacterial, it can move from one eye to both eyes. However, it may just stay in one.