Conjunctivitis is inflammation of the conjunctiva. The conjunctiva is a thin layer of tissue that covers the inside of the eyelids and the sclera. Conjunctivitis may be bacterial, viral or allergic. It may be unilateral or bilateral.
Presentation
Conjunctivitis presents with:
- Red, bloodshot eye
- Itchy or gritty sensation
- Discharge
Conjunctivitis does not cause pain, photophobia or reduced visual acuity. Discharge covering the eye may cause blurry vision, but this should return to normal when the discharge is cleared.
Bacterial conjunctivitis presents with a purulent discharge. It is typically worse in the morning when the eyes may be stuck together. It usually starts in one eye and can spread to the other. It is highly contagious.
Viral conjunctivitis is common and usually presents with a clear discharge. It is often associated with other symptoms of a viral infection, such as a dry cough, sore throat and blocked nose. There may be tender pre-auricular lymph nodes (in front of the ears). It is also contagious.
Causes of Acute Red Eye
Causes of an acute painful red eye include:
- Acute angle-closure glaucoma
- Anterior uveitis
- Scleritis
- Corneal abrasions or ulceration
- Keratitis
- Foreign body
- Traumatic or chemical injury
Causes of an acute painless red eye include:
- Conjunctivitis
- Episcleritis
- Subconjunctival haemorrhage
Conditions that require emergency same-day referral to ophthalmology tend to cause pain or reduced visual acuity.
Management
Conjunctivitis usually resolves in 1-2 weeks without needing treatment (even bacterial cases).
Hygiene measures can reduce spreading (e.g., avoiding towel sharing and close contact, and regular hand washing). Cleaning the eyes with cooled boiled water and cotton wool can help clear the discharge.
Chloramphenicol or fusidic acid eye drops are options for bacterial conjunctivitis if necessary.
Neonates under one month with conjunctivitis need urgent ophthalmology assessment. Neonatal conjunctivitis may be caused by gonococcal infection, which can cause serious complications (e.g., permanent vision loss).
Allergic Conjunctivitis
Allergic conjunctivitis is caused by contact with allergens. It causes swelling of the conjunctival sac and eyelid with itching and a watery discharge.
Antihistamines (oral or topical) can help symptoms.
Topical mast-cell stabilisers can be used in patients with chronic seasonal symptoms. They work by preventing mast cells from releasing histamine. These require several weeks of use before they show any benefit.
Last updated October 2023