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Acute Conjunctivitis

ROUTINE — Conjunctiva

Symptoms

General

  • Red eye (conjunctival hyperemia) and foreign body sensation.
  • Eyelids sticking or crusting on awakening.
  • Duration <4 weeks (otherwise consider chronic conjunctivitis).

Viral (adenovirus)

  • Itching, burning, tearing, and gritty sensation.
  • Recent URI or sick contact; often starts unilateral then involves fellow eye.

Bacterial

  • Mucopurulent yellow-green discharge with minimal itching.

Allergic

  • Bilateral itching (hallmark symptom).
  • Watery discharge and history of allergies.

Chlamydial & gonococcal

  • Chlamydial: Chronic (>3 weeks) unilateral discharge in sexually active adult.
  • Gonococcal: Hyperacute (12–24h) copious purulent discharge, chemosis, and lid edema.

Clinical Findings

Viral (adenovirus / EKC)

  • Follicular reaction on lower tarsus (pale dome-shaped nodules).
  • Tender ipsilateral preauricular lymph node (nearly pathognomonic).
  • Watery/serous discharge (crusted but not purulent on awakening).
  • EKC specific: Fine intraepithelial microcysts (early); subepithelial infiltrates (SEIs) appearing 1–2 weeks later; tarsal pseudomembranes in severe cases.

Bacterial

  • Papillary reaction (cobblestone upper tarsus).
  • Mucopurulent yellow-green discharge; eyelids matted shut.
  • Preauricular lymph node absent (key bedside discriminator from viral).

Special etiologies

  • Herpes simplex: Unilateral follicles, preauricular node, and vesicular periocular/lid-margin lesions.
  • Hyperacute gonococcal: Copious purulent discharge, marked chemosis, and rapid risk of corneal ulceration/perforation.
  • Chlamydial (adult inclusion): Chronic unilateral follicular reaction in a sexually active adult.

Etiology

Viral

  • Adenovirus (most common overall): Serotypes 3, 4, 7 (pharyngoconjunctival fever); Serotypes 8, 19, 37 (epidemic keratoconjunctivitis).
  • Herpes simplex: Primary infection in children/young adults.

Bacterial

  • Pediatric: H. influenzae (often with otitis media), S. pneumoniae, M. catarrhalis.
  • Adult: S. aureus (associated with blepharitis), S. epidermidis.
  • Hyperacute: Neisseria gonorrhoeae (most aggressive) or N. meningitidis.

Chlamydial & neonatal

  • Chlamydia (Serotypes D–K): Chronic follicular conjunctivitis in sexually active adults.
  • Neonatal timeline: Day 1 (chemical), Days 2–5 (gonococcal), Days 5–14 (chlamydial).

Allergic

  • Seasonal or perennial; bilateral itching is pathognomonic.

Red Flags

Clinical emergencies

  • Hyperacute purulent discharge (<24h) → treat as gonococcal (perforation risk).
  • Unilateral follicular conjunctivitis >3 weeks → chlamydial until proven otherwise.
  • Vesicular lid lesions or dendritic keratitis → herpes simplex (steroids contraindicated).
  • Progressive vision loss, corneal infiltrate, or hypopyon → rule out bacterial keratitis or endophthalmitis.

Infection control

  • EKC is highly contagious for 10–14 days; survives on surfaces for weeks.
  • Dedicated exam rooms and immediate tonometer/slit-lamp disinfection required.

Patient instructions

  • Stay home from work/school; no shared towels, pillows, or makeup.
  • Rigorous hand hygiene and discard any eye drops used during illness.

Investigations

Clinical evaluation

  • History and slit-lamp exam are primary; look for follicles vs. papillae.
  • Palpate for preauricular lymphadenopathy.
  • Fluorescein staining to check for corneal involvement (SPK, dendrites, ulcer).

Lab testing

  • Gram stain/culture (Chocolate/Thayer-Martin) for hyperacute purulent discharge.
  • PCR/NAAT of conjunctival scrapings for suspected chlamydial cases.
  • STI workup and partner referral for confirmed gonococcal or chlamydial cases.

Treatment

Viral / EKC

  • Supportive: PF artificial tears 4–8×/day and cool compresses.
  • Peel pseudomembranes to prevent symblepharon.
  • Topical steroids (loteprednol 0.5% QID) only for membranes or visually significant SEIs.

Bacterial

  • Topical trimethoprim/polymyxin B or fluoroquinolone QID for 5–7 days.
  • Oral amoxicillin-clavulanate for H. influenzae to prevent systemic spread.

Gonococcal & chlamydial

  • Gonococcal: Ceftriaxone 1g IM single dose + Azithromycin 1g PO (for co-existing chlamydia).
  • Chlamydial: Azithromycin 1g PO once OR Doxycycline 100mg BID for 7 days.
  • Saline irrigation until discharge resolves in gonococcal cases.

Allergic

  • Antihistamine/mast-cell stabilizers (olopatadine, alcaftadine, ketotifen).
  • Mild topical steroids (loteprednol 0.2% QID) for severe cases.

Special conditions

  • HSV: Oral acyclovir; no topical steroids without antiviral cover.
  • Pediculosis: Mechanical removal of lice/eggs + erythromycin ointment to lid margins TID.

Clinical Pearl

The key question in red eye is "does the cornea stain?" — pure conjunctivitis has a clear cornea; a staining cornea means keratitis, ulcer, or HSV and requires a completely different treatment path.

Differential Diagnosis

  • Acute angle closure glaucoma
  • Anterior uveitis (iritis)
  • Episcleritis
  • Subconjunctival hemorrhage
  • Corneal abrasion
  • Bacterial keratitis

Related Conjunctiva Conditions