Differential Diagnosis of Viral Conjunctivitis

Primary Infectious Differentials

The American Academy of Ophthalmology suggests that nongonococcal bacterial conjunctivitis presents with purulent or mucopurulent discharge, often with eyelids matted shut upon awakening, in patients with suspected viral conjunctivitis 1
Hyperacute gonococcal conjunctivitis is a critical differential diagnosis, presenting with copious purulent discharge, marked eyelid edema, preauricular lymphadenopathy, and risk of superior corneal infiltrates that can perforate within 24 hours, according to the American Academy of Ophthalmology 3
The American Academy of Ophthalmology notes that HSV conjunctivitis usually presents unilaterally with a mild follicular reaction, may have vesicular lesions on eyelids or dendritic corneal lesions, and subsides in 4-7 days unless complications occur 1, 4
Varicella-zoster virus (VZV) conjunctivitis is characterized by a distinctive vesicular dermatomal rash or ulceration of eyelids, pleomorphic pseudodendritic epithelial keratitis, and typically subsides in a few days, as stated by the American Academy of Ophthalmology 1, 4
Molluscum contagiosum conjunctivitis presents with shiny, dome-shaped umbilicated lesion(s) on eyelid skin or margin with associated follicular conjunctivitis, and is more common in immunocompromised patients, according to the American Academy of Ophthalmology 1, 4

The American Academy of Ophthalmology states that allergic conjunctivitis presents bilaterally with eyelid edema, chemosis, watery discharge, and papillary (not follicular) palpebral reaction, and is associated with environmental allergens, seasonal patterns, and personal/family history of atopy 2
Dry eye (keratoconjunctivitis sicca) is the most frequent cause of conjunctival inflammation, requiring treatment of underlying tear film dysfunction, as noted by the American Academy of Ophthalmology 2
Blepharitis is another common cause of secondary conjunctival inflammation, and treatment must address eyelid margin disease, according to the American Academy of Ophthalmology 2

The American Academy of Ophthalmology recommends considering discharge type, laterality, follicles vs papillae, and preauricular lymphadenopathy when differentiating between viral, bacterial, and allergic conjunctivitis 1, 3, 7
The American Academy of Ophthalmology suggests that copious purulent discharge with marked eyelid edema is indicative of hyperacute bacterial conjunctivitis, requiring immediate systemic ceftriaxone 1g IM/IV without waiting for cultures 3
Corneal involvement (infiltrates, ulcers) requires urgent ophthalmology referral and systemic antibiotics, as stated by the American Academy of Ophthalmology 3
A vesicular rash on eyelids or nose is indicative of HSV/VZV, requiring antiviral therapy and ophthalmology evaluation, according to the American Academy of Ophthalmology 1
Neonatal conjunctivitis is an emergency until gonococcal and chlamydial causes are excluded, as noted by the American Academy of Ophthalmology 6

Delaying systemic antibiotics in suspected gonococcal conjunctivitis can lead to corneal perforation and permanent vision loss, as warned by the American Academy of Ophthalmology 3
Overlooking serious conditions such as uveitis, acute angle-closure glaucoma, or scleritis that may present with conjunctival hyperemia is a common pitfall, according to the American Academy of Ophthalmology 7
Failing to identify underlying ocular surface disease (dry eye, blepharitis) that may be the primary problem rather than true infectious conjunctivitis is a critical mistake, as stated by the American Academy of Ophthalmology 2