Viral conjunctivitis

Epidemiology & Risk Factors

• Most common cause of infectious conjunctivitis in adults and children.
• Etiology: Adenovirus (>80% of cases); occasionally Enterovirus, Coxsackievirus, HSV.
• Transmission: Direct contact with infected secretions, fomites, contaminated swimming pools.
• Risk factors:
  • Recent viral URI prodrome (pharyngitis, fever).
  • Crowded environments (schools, daycares, military barracks).
  • Contact with an infected individual.

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Clinical Features

• History:
  • Acute onset of eye redness and gritty/sandpaper sensation.
  • Classically starts unilateral and rapidly spreads to the bilateral eye within 24–48 hours.
  • Copious watery/serous discharge (minimal or non-purulent crusting).
  • Associated systemic symptoms: Sore throat, low-grade fever, rhinitis (pharyngoconjunctival fever). c
• Physical Examination:
  • Preauricular lymphadenopathy (hallmark clinical clue).
  • Diffuse conjunctival injection/hyperemia and mild chemosis.
  • Follicular reaction (tiny, pale bumps) on the palpebral conjunctiva. c
  • Normal visual acuity, normal pupillary light reflexes, clear cornea (unless complicated by keratitis).

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Diagnosis

• Initial & Best Step: Clinical diagnosis (based on watery discharge + preauricular LAD + URI symptoms).
• Confirmatory / Gold Standard: Viral cell culture or PCR of conjunctival swab (rarely indicated; reserved for atypical or severe cases).
• Fluorescein Staining: Indicated to rule out corneal involvement or dendritic ulcers (HSV keratitis).

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Differential Diagnostics

• Bacterial Conjunctivitis:
  • Diff by thick, copious purulent discharge that re-accumulates immediately after wiping; eye glued shut upon awakening; typically lacks preauricular LAD (except N. gonorrhoeae).
• Allergic Conjunctivitis:
  • Diff by severe, prominent bilateral pruritus (itching); marked chemosis; stringy mucoid discharge; history of atopy; no preauricular LAD.
• Herpes Simplex Keratoconjunctivitis:
  • Diff by unilateral involvement, severe photophobia, decreased corneal sensation, and dendritic branching ulcers on fluorescein exam.
• Anterior Uveitis (Iritis):
  • Diff by ciliary flush (perilimbal injection), consensual photophobia, constricted pupil, and cells/flare in the anterior chamber on slit-lamp exam.
• Acute Angle-Closure Glaucoma:
  • Diff by severe ocular pain, headache, nausea/vomiting, fixed mid-dilated pupil, cloudy/steamy cornea, and markedly elevated IOP (>30 mmHg).

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Management

1. First-line (Symptomatic & Supportive):
   • Cold compresses and chilled artificial tears.
   • Topical OTC antihistamine/decongestant drops for symptomatic relief.
2. Infection Control & Education:
   • Highly contagious for 10–14 days.
   • Strict hand hygiene, avoid rubbing eyes, do not share towels or pillows.
   • Discontinue contact lens wear until symptoms completely resolve.
3. Refractory / Vision-Threatening (Ophthalmology Referral):
   • Urgent consult if severe photophobia, foreign body sensation, or decreased visual acuity.
   • Topical corticosteroids (prescribed only by ophthalmology after excluding HSV) for disabling subepithelial infiltrates.

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Complications

• Epidemic Keratoconjunctivitis (EKC): Adenovirus serotypes 8, 19, 37 causing corneal involvement with subepithelial infiltrates, photophobia, and transiently decreased visual acuity.
• Secondary bacterial superinfection.
• Corneal ulceration or permanent visual impairment if misdiagnosed HSV is inappropriately treated with topical steroids.