Conjunctivitis - clinical fact sheet and MCQ

Overview

Conjunctivitis refers to inflammation of the conjunctiva, the transparent membrane covering the sclera and inner eyelids. Conjunctivitis is a frequent presentation in general practice and may be caused by infective or non-infective aetiologies. The most common infectious aetiology among adults is viral. It is highly contagious but self-limiting. 

Non-infectious aetiologies include autoimmune, allergy, and drug related. Prompt identification of the underlying cause is essential to guide appropriate management and reduce unnecessary antibiotic use or missed serious pathology such as keratitis.

Neonatal conjunctivitis requires urgent, hospital-based care and is not covered in this FastTrack.

Diagnosis of conjunctivitis

1. Clinical assessment

It is important to consider the patient’s age and risk factors as the diagnosis is predominantly clinical, based on history, symptom pattern, and examination findings. 

Differentiation between viral, bacterial, allergic, and atypical causes is crucial. Key diagnostic clues are summarised below.

• Viral conjunctivitis often starts in one eye and becomes bilateral on day 2-4. It presents with watery or mucoid discharge, irritation, itching, conjunctival injection, and tender preauricular lymphadenopathy. It is frequently associated with upper respiratory tract symptoms and is most commonly caused by adenovirus.
• Bacterial conjunctivitis features conjunctival injection, purulent discharge, and eyelid crusting from one or both eyes. Patients typically do not complain of itch. Common organisms include Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae.
• Chlamydial conjunctivitis is typically a follicular conjunctivitis, unilateral, with a sticky discharge and is often accompanied by a tender pre-auricular node. It should be considered in patients with conjunctivitis (especially unilateral) that has persisted for more than a few weeks.
• Gonococcal conjunctivitis is often unilateral initially and causes hyperacute conjunctivitis, associated with a mucopurulent or hyperpurulent discharge. Gonococcal conjunctivitis can cause corneal ulceration and rapid perforation and  warrants urgent ophthalmic review.
• Allergic conjunctivitis is usually bilateral, with intense itching, watery or mucoid discharge, and seasonal or perennial triggers. It may be associated with other allergic symptoms such as rhinitis.
• Autoimmune conjunctivitis is a rarer, but important cause of conjunctivitis. It is associated with mucous membrane pemphigoid, Stevens-Johnson syndrome and toxic epidermal necrolysis.
• Drug related: drugs can cause a contact allergic conjunctivitis (eg apraclonidine eye drops), or an inflammatory reaction, eg with bisphosphonates. 
  
  

2. Red flags requiring urgent referral to ophthalmology:

• neonates (outside the scope of this FastTrack)
• significant pain, photophobia
• reduced visual acuity not attributable to disturbance from discharge
• persistent or worsening symptoms despite treatment
• membrane or pseudomembrane formation
• suspected keratitis or corneal involvement
  • high index of suspicion in contact lens wearers
• suspected atypical pathogens eg gonococcal, chlamydial conjunctivitis 
  
  

3. Differential diagnosis: 

• microbial keratitis: corneal infection resulting in pain, photophobia and reduced vision, requiring prompt and intensive topical antibiotic treatment
• anterior uveitis: anterior segment inflammation, typically with pain and photophobia, and can have reduced vision
• acute angle closure glaucoma: acutely red, painful eye with mid-dilated pupil. Associated with corneal clouding due to raised pressure
• corneal foreign body or abrasion: may be visualised with fluorescein, foreign body sensation
• orbital cellulitis: eyelid swelling, pain with extraocular movement, reduced eye movement, diplopia
• cavernous carotid fistula: is rare and typically produces ‘cork screw’ conjunctival vessels due to raised venous pressure due to abnormal connection between arterial and venous systems
• dry eye: more chronic presentation, ocular discomfort, corneal epitheliopathy on fluorescein staining
• subconjunctival haemorrhage: due to extravasated blood, rather than engorged blood vessels
  
  

4. Investigations

Most cases do not require laboratory tests. However, conjunctival swabs for Gram stain, culture, and PCR are recommended in the following scenarios:

• persistent or recurrent conjunctivitis
• conjunctivitis not responding to treatment
• suspected chlamydial or gonococcal aetiology – either at acute presentation, or in subacute conjunctivitis not attributable to allergy/autoimmune/drug related (eg mucopurulent discharge, no itch)
  
  

Management of conjunctivitis in primary practice

Management depends on the aetiology. Most cases are self-limiting and can be managed symptomatically in primary care. Emphasis should be placed on patient education about hygiene to prevent transmission, especially in viral cases.

1. Viral conjunctivitis

Treatment is supportive:

• cool compresses
• frequent lubricant eye drops for comfort
• strict hygiene: handwashing, avoidance of touching eyes, not sharing towels or linen

Patients should stay away from work, school, childcare, and healthcare settings while symptomatic. Topical corticosteroids should be avoided unless advised by an ophthalmologist. Refer to an ophthalmologist if any deterioration, especially reduced vision or photophobia.

2. Bacterial conjunctivitis

Most cases resolve within seven days without treatment. However, there is evidence suggesting topical antibiotics speed recovery. Consider prescribing topical antibiotics (eg chloramphenicol 0.5% qid for 5-7 days) if:

• symptoms are marked (eg purulent discharge)
• symptoms persist

Instruct patients to clean discharge before instilling drops with cooled, boiled water. Avoid aminoglycosides and quinolones empirically due to risk of hypersensitivity reactions.

3. Chlamydial conjunctivitis

Requires systemic treatment and specialist referral for treatment with oral azithromycin or doxycycline depending on the age of the patient.

Evaluate for coinfections and STI screening.

4. Gonococcal conjunctivitis

Is an ophthalmic emergency requiring immediate referral. The patient should be evaluated for co-infections and STI screening. Topical antibiotics are inadequate alone.

Begin empirical treatment:

• children: ceftriaxone 50 mg/kg (IM/IV) OR cefotaxime 100 mg/kg (IM/IV) as single dose
  • gonococcal  conjunctivitis in a child, outside the neonatal period, should always lead to suspicion of sexual abuse and be referred appropriately
• adults: ceftriaxone 1 g IM/IV PLUS azithromycin 1 g orally
  
  

5. Allergic conjunctivitis

No antibiotics are required. Management includes:

• allergen avoidance
• management of allergic rhinitis
• lubricant or antihistamine eye drops
• cool compresses
• oral antihistamine if associated with systemic symptoms
• referral to ophthalmology in refractory or severe cases
  
  

6. Conjunctivitis in contact lens wearers

Contact lens wearers are at greater risk of sight-threatening microbial keratitis compared to non-contact lens wearers, particularly if in extended (overnight) wear lenses or non-compliant with hygiene practices. 

A common complication of contact lens wear is giant papillary conjunctivitis (GPC). This presents as large papillae on the superior palpebral conjunctiva with hyperaemia, visible with lid eversion, and contact lens intolerance. 

These patients are also at higher risk of sight threatening fungal and acanthamoeba corneal infection, in which topical steroid is contraindicated. 

• Advise patients to cease contact lens wear immediately, and discard lenses
• Refer if GPC suspected/conjunctivitis without visual disturbance
• Refer if bacterial conjunctivitis or microbial keratitis suspected
  
  

References

1. Therapeutic Guidelines. Conjunctivitis. 2025. Available at: https://app.tg.org.au/viewTopic?etgAccess=true&guidelinePage=Antibiotic&topicfile=bartonella-infections&guidelinename=auto&sectionId=r_ABG_Conjunctivitis_topic_13#r_ABG_Conjunctivitis_topic_13. (last accessed May 2025).
   
2. Gin C, Crock C, Wells K. Conjunctivitis: A review. AJGP. 2024 Nov;53(11). Available from: https://www1.racgp.org.au/ajgp/2024/november/conjunctivitis.
3. Royal Victorian Eye and Ear Hospital. Viral Conjunctivitis Clinical Practice Guideline. 2022. Available from: https://eyeandear.org.au/health-professionals/clinical-practice-guidelines/. (last accessed May 2025).
   
4. Oong GC, Tadi P. Chloramphenicol. [Updated 2023 Jul 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025. Available from: https://www.ncbi.nlm.nih.gov/books/NBK555966/. (last accessed May 2025).
5. Prabakaran S, Mahmud H, Bansal S, et al. Membranous conjunctivitis and pseudomembranous conjunctivitis. 2025. Available at: https://eyewiki.org/Membranous_Conjunctivitis_and_Pseudomembranous_Conjunctivitis#:~:text=Medical%20therapy%20and%20follow%20Management%20of%20Pseudomembranous,identified.%20Topical%20steroids%20can%20reduce%20ocular%20inflammation. (last accessed Sept 2025).

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