What are the key clinical features to differentiate between viral and bacterial keratitis in a primary care setting?

In a primary care setting, accurate differentiation between viral and bacterial keratitis typically requires specialist ophthalmological assessment, including slit-lamp examination ¹. For suspected ocular herpes simplex infection, a form of viral keratitis, all cases should be referred to eye casualty or an emergency eye service for same-day assessment and specialist management ¹. The guidelines emphasize that delayed diagnosis, misdiagnosis, or inappropriate treatment can lead to serious and/or sight-threatening sequelae ¹. For instance, inappropriate use of topical or systemic corticosteroids in primary care may transform a simple herpetic dendritic ulcer into an extensive amoeboid ulcer, potentially causing corneal scarring and visual loss, and can aggravate infections caused by other pathogens ¹. Therefore, specific clinical features for primary care differentiation are not detailed, with the emphasis placed on prompt specialist referral for diagnosis and management ¹.