Highly contagious viral inflammation of conjunctiva — typically adenovirus; supportive care only.
Also known as: viral conjunctivitis, pink eye viral, adenoviral conjunctivitis, epidemic keratoconjunctivitis, EKC
Overview
Self-limited inflammation of the conjunctiva caused by a virus, most often adenovirus. Subtypes include pharyngoconjunctival fever (adenovirus 3, 7), epidemic keratoconjunctivitis (EKC, adenovirus 8, 19, 37 — corneal involvement), HSV/VZV conjunctivitis, and enterovirus 70 acute hemorrhagic conjunctivitis.
Epidemiology
Most common type of infectious conjunctivitis in adults. Highly contagious by direct contact and fomites; outbreaks occur in schools, camps, military barracks, healthcare facilities. Incubation 5-12 days; contagious during symptoms and up to 14 days after onset.
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Question 1EENTMedium
A 24-year-old man presents with a 3-day history of a red, watery right eye that has now spread to the left eye. He reports a gritty, foreign-body sensation and clear, profuse tearing but denies significant itching. He had a sore throat and low-grade fever the prior week. On exam, both eyes show diffuse bulbar conjunctival injection with a follicular reaction on the tarsal conjunctiva and watery (non-purulent) discharge. A tender, palpable preauricular lymph node is noted on the right. Visual acuity is normal, and fluorescein staining shows no corneal dendrites. Which of the following is the most likely diagnosis?
AAdenoviral conjunctivitis
BGonococcal conjunctivitis
CAllergic conjunctivitis
DHSV keratoconjunctivitis
Reveal answer & full explanation
Correct answer: A — Adenoviral conjunctivitis
AAdenoviral conjunctivitis✓
BGonococcal conjunctivitis
CAllergic conjunctivitis
DHSV keratoconjunctivitis
Why Adenoviral conjunctivitis is correct
The classic triad is present: a watery red eye with a follicular tarsal reaction, ipsilateral tender preauricular lymphadenopathy, and an antecedent upper respiratory infection (sore throat, fever) in a young adult.
Adenovirus is the most common cause, and this URI-plus-bilateral-conjunctivitis picture is pharyngoconjunctival fever; spread from one eye to the fellow eye over days is typical, and the disease is self-limited (1-3 weeks) requiring only supportive care (cool compresses, artificial tears, strict hygiene).
Tender preauricular adenopathy supports a viral (or gonococcal) etiology and is usually absent in routine allergic conjunctivitis.
Why the others are wrong
Gonococcal conjunctivitis - although it can also produce a preauricular node, it causes hyperacute (under 24 hours) copious purulent discharge with marked lid edema; this patient has a 3-day course with watery, non-purulent discharge.
Allergic conjunctivitis - itching is the hallmark, usually with an atopic history and chemosis; this patient explicitly denies significant itching and has a preceding URI instead.
HSV keratoconjunctivitis - would show a dendritic corneal ulcer on fluorescein staining (often with decreased corneal sensation or lid vesicles); fluorescein here is negative, and empiric topical steroids must be avoided if HSV is suspected.
Question 2EENTMedium
A 24-year-old elementary school teacher presents with 3 days of a watery red right eye that is now spreading to the left eye. She reports a gritty foreign-body sensation and a recent sore throat. On exam, she has diffuse bulbar conjunctival injection with a follicular reaction on the tarsal conjunctiva, watery discharge, and a tender right preauricular node; fluorescein staining shows no dendrites. She notes that a coworker had identical symptoms last week, and the two often share the same desk and hand towel in the breakroom. Which of the following is the strongest risk factor for this patient's condition?
AContact with an infected individual
BChronic eyelid margin inflammation
CHistory of seasonal allergic rhinitis
DExtended-wear soft contact lens use
Reveal answer & full explanation
Correct answer: A — Contact with an infected individual
AContact with an infected individual✓
BChronic eyelid margin inflammation
CHistory of seasonal allergic rhinitis
DExtended-wear soft contact lens use
Why Contact with an infected individual is correct
This patient has classic adenoviral (viral) conjunctivitis: watery follicular red eye, tender preauricular lymphadenopathy, recent URI/sore throat, and spread to the fellow eye, with no dendrites on fluorescein staining.
Adenovirus is extraordinarily contagious by direct contact and fomites (towels, fingers, shared surfaces, ophthalmic equipment), which is why outbreaks cluster in schools, camps, barracks, and clinics; a sick close contact plus a shared hand towel is the single strongest exposure here.
Hand washing and not sharing towels are the most effective measures to prevent spread, underscoring contact/fomite transmission as the dominant risk factor.
Why the others are wrong
History of seasonal allergic rhinitis: Atopy is the risk factor for ALLERGIC conjunctivitis, whose hallmark is bilateral itching with stringy mucus and no preauricular node; it does not drive viral conjunctivitis.
Extended-wear soft contact lens use: Contact lens wear predisposes to bacterial/microbial keratitis (e.g., Pseudomonas), not adenoviral conjunctivitis; lenses should simply be discarded during recovery here.
Chronic eyelid margin inflammation: Blepharitis causes chronic crusting and dry-eye irritation but is not a transmission-related risk factor for an acute, highly contagious viral conjunctivitis.
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Healthcare exposure (notable in clinics with shared instruments — tonometer prisms)
Recent ocular trauma or surgery (HSV reactivation)
Pathophysiology
Adenoviral infection of conjunctival epithelium leads to lymphocyte and macrophage infiltration. EKC involves additional invasion of corneal epithelium and subepithelial stroma, leading to characteristic subepithelial corneal infiltrates that can persist for months. HSV ocular infection typically produces dendritic keratitis with conjunctivitis. Enterovirus 70 produces subconjunctival hemorrhages with bilateral conjunctivitis.
Clinical presentation
Symptoms
Acute red eye, often beginning unilateral and spreading to fellow eye within days
Watery discharge — clear, profuse
Foreign body or gritty sensation, burning
Mild eyelid swelling and crusting (less than bacterial)
Photophobia and decreased vision suggest corneal involvement (EKC, HSV)
Signs / physical exam
Diffuse bulbar conjunctival injection with follicular reaction on tarsal conjunctiva
Watery, sometimes mucoid, discharge
Tender preauricular lymphadenopathy — characteristic of viral and gonococcal conjunctivitis
Punctate keratitis or subepithelial corneal infiltrates in EKC (slit lamp)
Pseudomembrane on tarsal conjunctiva in severe EKC
Dendritic corneal ulcer on fluorescein staining → HSV (treat with antivirals; AVOID corticosteroids)
Classic findings
Watery red eye with follicular reaction, ipsilateral preauricular lymphadenopathy, and recent URI in an adult.
Differential diagnosis
Bacterial conjunctivitis — Purulent discharge throughout day, eyelids matted shut on awakening, minimal itching, no preauricular node
Allergic conjunctivitis — Itching is hallmark, bilateral, watery discharge with stringy mucus, atopic history, chemosis
HSV keratoconjunctivitis — Dendritic ulcer on fluorescein staining, vesicles on lid, decreased corneal sensation; topical and/or oral antivirals; do NOT give topical steroid empirically
Severe conjunctivitis, subepithelial corneal infiltrates, pseudomembranes
Supportive ± steroids by ophthalmology
HSV keratoconjunctivitis
Dendritic ulcer on fluorescein, unilateral
Topical/oral antivirals; AVOID empiric steroids
Herpes zoster ophthalmicus (VZV)
V1 vesicles, Hutchinson sign
Oral acyclovir/valacyclovir; ophthalmology
Acute hemorrhagic conjunctivitis (enterovirus 70)
Subconjunctival hemorrhages, bilateral
Supportive
Common viral conjunctivitis subtypes and their distinguishing features.
Treatment
First-line
Supportive care — viral conjunctivitis is self-limited (1-3 weeks)
Cool compresses to reduce swelling
Artificial tears for lubrication and symptom relief
Strict hygiene: hand washing, no shared towels/pillows/eye drops, no cosmetics, no contact lens wear until resolved
Stay home from school/work until tearing and discharge resolve (typically 7-14 days)
Discard contact lenses and case after recovery
Second-line / adjunct
HSV keratoconjunctivitis: trifluridine 1% drops 9×/day OR ganciclovir 0.15% gel 5×/day OR oral acyclovir 400 mg 5×/day; ophthalmology referral; do NOT give empiric topical corticosteroids — they can worsen HSV epithelial keratitis
Severe EKC with pseudomembranes or visually significant subepithelial infiltrates: topical corticosteroids ONLY under ophthalmologist direction (HSV must be excluded)
Avoid topical antibiotics — no benefit in viral disease and contribute to resistance
Ophthalmology referral for: HSV/VZV, contact lens wear, severe symptoms, decreased vision, photophobia, no improvement after 7-10 days
Complications
Spread to fellow eye and household/work contacts
Subepithelial corneal infiltrates with persistent blurred vision (EKC) — months
Symblepharon (conjunctival scarring) with pseudomembranes
HSV stromal keratitis and recurrent disease with vision loss
Bacterial superinfection (rare)
Healthcare-associated outbreaks if equipment not disinfected (tonometer prisms)
PANCE pearls
Tender preauricular lymphadenopathy supports viral (or gonococcal) etiology — usually absent in routine bacterial or allergic.
Epidemic keratoconjunctivitis (EKC) — highly contagious; subepithelial corneal infiltrates can blur vision for months. Quarantine and disinfect equipment with bleach (alcohol does NOT kill adenovirus).
Dendritic ulcer on fluorescein staining = HSV keratitis — antivirals, NEVER empiric topical steroids.
Hutchinson sign (vesicle on nasal tip) heralds ocular involvement in herpes zoster ophthalmicus — urgent ophthalmology consult.
Hand washing and not sharing towels are the most effective measures to prevent spread.
References
AAO 2018 — American Academy of Ophthalmology. Conjunctivitis Preferred Practice Pattern. Ophthalmology 2019;126(1):P94-P169
CDC — Centers for Disease Control and Prevention. Adenovirus and Healthcare-Associated Conjunctivitis Outbreaks. 2022
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