Conjunctivitis
Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management
Definition
Conjunctivitis is an inflammation of the conjunctiva, which can be infectious (viral or bacterial) or non infectious (allergic or irritant induced), leading to redness, discomfort, and ocular discharge.
Aetiology
- Viral: Adenovirus (most common), herpes simplex virus (HSV).
- Bacterial: Staph. aureus, Strep. pneumoniae, H. influenzae, N. gonorrhoeae.
- Allergic: Seasonal allergens (pollen, dust mites, pet dander).
- Irritant: Smoke, chlorine, chemicals, foreign bodies.
Pathophysiology
- Infectious conjunctivitis involves microbial invasion, leading to inflammation and increased mucus production.
- Allergic conjunctivitis results from histamine release, causing vascular dilation and conjunctival oedema.
- Irritant conjunctivitis arises from direct chemical or mechanical irritation.
Risk Factors
- Close contact with infected individuals (viral/bacterial).
- Use of contaminated contact lenses.
- History of allergic rhinitis or atopy.
- Exposure to environmental irritants.
Signs and Symptoms
- Viral conjunctivitis: watery discharge, foreign body sensation, preauricular lymphadenopathy.
- Bacterial conjunctivitis: purulent discharge, eyelid crusting, conjunctival injection.
- Allergic conjunctivitis: itching, watery discharge, bilateral involvement, chemosis.
- Irritant conjunctivitis: burning, redness, history of exposure to irritants.
Investigations
- Clinical diagnosis: based on history and examination.
- Swab for culture: in severe or persistent bacterial cases.
- Fluorescein staining: to exclude corneal involvement (e.g., keratitis, ulcer).
- Allergy testing: if allergic conjunctivitis is recurrent.
Management
1. Viral Conjunctivitis:
- Supportive care (artificial tears, cold compresses).
- Good hygiene to prevent spread.
- Topical antihistamines if significant irritation.
2. Bacterial Conjunctivitis:
- Topical antibiotics (chloramphenicol drops or fusidic acid for severe cases).
- Advise on hand hygiene to reduce transmission.
3. Allergic Conjunctivitis:
- Topical antihistamines (olopatadine, ketotifen).
- Oral antihistamines if systemic symptoms present.
- Avoidance of known allergens.
4. Irritant Conjunctivitis:
- Remove offending agent.
- Lubricating eye drops.
5. Referral:
- Ophthalmology: if symptoms persist despite treatment, suspicion of keratitis, or vision impairment.
- Allergy specialist: if severe or recurrent allergic conjunctivitis.