Conjunctivitis - infective
Exam Tips
- In OSCEs, always check and document visual acuity first in any red-eye presentation.
- Viral vs bacterial features overlap; examiners reward recognition of uncertainty plus safe safety-netting.
- Copious rapidly progressive purulent discharge is gonococcal until proven otherwise: same-day ophthalmology and sexual health referral.
- Contact lens wearer with pain or photophobia should be managed as possible keratitis, not simple conjunctivitis.
- Neonatal red sticky eye (within 30 days) is an emergency because delayed treatment can cause sight-threatening disease.
- Do not start topical steroid eye drops in primary care for undifferentiated conjunctivitis.
- Image anchor: compare follicles (viral/chlamydial) versus papillae (allergic) on upper lid eversion; see standard slit-lamp teaching figure for tarsal conjunctival changes.
Definition
Infective conjunctivitis is inflammation of the bulbar and/or palpebral conjunctiva caused by microorganisms, most commonly adenoviruses and common bacterial pathogens such as Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae. It typically presents as an acute red eye with discomfort and discharge, and is usually self-limiting, but specific subtypes (for example gonococcal infection, herpes-related disease, contact lens-associated keratitis risk, or neonatal disease) can threaten sight and require urgent specialist care.
Pathophysiology
Pathogens infect the conjunctival epithelium and trigger innate and adaptive inflammatory responses (cytokine release, vasodilation, increased vascular permeability), causing conjunctival hyperaemia, chemosis, and discharge. Viral disease (especially adenovirus) is often follicular with watery discharge and may involve the cornea (epidemic keratoconjunctivitis), where subepithelial infiltrates can reduce vision and cause photophobia. Bacterial disease tends to produce neutrophil-rich purulent or mucopurulent exudate with lid crusting. Hyperacute gonococcal infection can penetrate intact epithelium rapidly, causing severe keratitis and risk of corneal perforation. In neonates, immature ocular surface defences and perinatal exposure to organisms (notably Chlamydia trachomatis or Neisseria gonorrhoeae) increase risk of invasive complications.
Risk Factors
- Close contact with an infected person (household/school outbreaks, especially adenovirus)
- Contact lens wear (particularly soft lenses), which increases risk of keratitis and Pseudomonas-related complications
- Immunocompromise (e. g. HIV, chemotherapy, systemic immunosuppression)
- Sexual exposure risk factors for chlamydial or gonococcal conjunctivitis
- Neonatal age (ophthalmia neonatorum within first 4 weeks of life)
- Recent upper respiratory tract infection (common with viral conjunctivitis)
- Recent ophthalmic surgery or ocular surface disruption
Clinical Features
Symptoms
- Acute red eye with grittiness, burning, or foreign-body sensation
- Watery discharge (more typical viral) or mucopurulent/purulent discharge (more typical bacterial)
- Lids stuck together on waking (classically bacterial)
- Transient blurring that clears with blinking/wiping discharge
- Itch may occur (usually mild in infective disease)
- Photophobia or marked pain suggests corneal/serious pathology rather than simple conjunctivitis
- Rapidly progressive copious discharge over 12-24 hours suggests gonococcal disease
- Chronic low-grade irritation for more than 2 weeks in sexually active adults suggests chlamydial conjunctivitis
Signs
- Conjunctival injection (often diffuse) and possible chemosis
- Follicles on palpebral conjunctiva (often viral/chlamydial) versus papillae (more allergic/contact lens intolerance)
- Pre-auricular lymphadenopathy (common in viral, can occur in hyperacute bacterial and chlamydial disease)
- Lid oedema and crusting; vesicles on eyelid may indicate herpes simplex
- Petechial subconjunctival haemorrhages or pseudomembranes in severe adenoviral disease
- Corneal staining/epithelial defect on fluorescein in contact lens-associated disease or keratitis
- Neonates: severe lid swelling and purulent discharge (gonococcal ON) or watery/mucopurulent discharge day 5-14 (chlamydial ON)
Investigations
Management
Lifestyle Modifications
- Advise strict hand hygiene, avoid sharing towels/pillows/cosmetics, and clean eyelid discharge with sterile water/cotton wool
- Temporarily stop contact lenses and discard current lenses/case; restart only when eye is white and asymptomatic for at least 24 hours
- Avoid school/work exclusion unless systemically unwell, but minimise close-contact spread during active discharge phase
- Provide safety-netting: urgent same-day review if pain, photophobia, reduced vision, worsening redness, corneal symptoms, or no improvement
Pharmacological Treatment
Topical broad-spectrum antibiotic (uncomplicated bacterial conjunctivitis where treatment is chosen)
- Chloramphenicol 0.5% eye drops: 1 drop every 2 hours for 48 hours, then every 4 hours while awake
- Chloramphenicol 1% eye ointment: apply 3-4 times daily (or at night with daytime drops)
Typical duration 5 days (or continue until 48 hours after symptom resolution per local protocol). Avoid in chloramphenicol hypersensitivity and use caution in people with previous bone marrow suppression/blood dyscrasia. Not first-line for contact lens-associated keratitis risk.
Alternative topical antibiotic
- Fusidic acid 1% viscous eye drops: 1 drop twice daily for 7 days
Useful when adherence to frequent dosing is difficult; narrower spectrum than chloramphenicol.
Supportive symptomatic treatment
- Ocular lubricants (e. g. carmellose sodium 0.5-1% drops as required)
- Oral analgesia such as paracetamol 500 mg-1 g every 4-6 hours (max 4 g/day)
Most viral cases are self-limiting; antibiotics are usually not required.
Specialist/systemic therapy for severe or specific pathogens
- Gonococcal conjunctivitis (adult): ceftriaxone 1 g IM single dose plus urgent ophthalmology/sexual health management
- Chlamydial conjunctivitis (adult): doxycycline 100 mg twice daily for 7 days (or azithromycin 1 g stat where appropriate)
Treat sexual partners and test for co-infections. Neonatal conjunctivitis requires same-day paediatric/ophthalmology input and protocol-driven systemic therapy.
Complications
- Epidemic keratoconjunctivitis with subepithelial corneal infiltrates causing persistent photophobia and reduced vision
- Keratitis, particularly in contact lens wearers or immunocompromised patients
- Corneal ulceration and perforation (high risk in gonococcal infection)
- Conjunctival scarring and severe dry-eye sequelae after membranous disease
- Ophthalmia neonatorum complications: corneal scarring, ulceration, globe perforation, endophthalmitis, pneumonia (chlamydial), permanent visual loss, and rarely mortality
Prognosis
Overall prognosis is good: most acute viral cases settle in about 7 days and most bacterial cases in 5-10 days, with low risk of permanent visual loss in uncomplicated disease. Adenoviral infection is contagious for around 10-14 days, and severe phenotypes (especially gonococcal, herpetic, contact lens-associated keratitis, and neonatal infection) carry a substantially worse prognosis without urgent treatment.
Sources & References
✅NICE Guidelines(1)
- Conjunctivitis - infective[overview]
📖Textbook References(3)
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1580)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1579, 1580)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1580)[context]