My cat has yellow eye discharge and can’t open its eyes—is it keratitis or conjunctivitis?

Yellow eye discharge with eyes that will not open first suggests bacterial or viral conjunctivitis, but keratitis or corneal injury from trauma or foreign bodies is also possible; the exact cause needs viral screening and an eye exam at a clinic. For mild cases, use neomycin sulfate eye drops at home after cleaning the inflammatory discharge daily, which eases discomfort and reduces bacteria for faster recovery. If the cat scratches its eyes from irritation, use an Elizabethan collar; apply drops 3-5 times daily, 2-3 drops each, and bacterial conjunctivitis often improves in 5-7 days, with anti-inflammatory pills once daily for 3-5 days, adjusted to the drug label.