Overview
Allergic conjunctivitis is an IgE-mediated hypersensitivity reaction due to exposure to allergens in sensitised patients leading to inflammation of the conjunctiva. These allergens are often pollen and symptoms are often seen in the context of hayfever.
The release of histamine and activation of histamine H1 receptors in the conjunctiva leads to eye itching, which is often the most predominant feature.
Epidemiology
- Allergic conjunctivitis is very common and affects 15-40% of the population
- Many patients with allergic rhinitis also have allergic conjunctivitis
- The prevalence of allergic conditions including allergic conjunctivitis has been increasing over the last few decades
Risk Factors
- Personal history of hayfever/other atopic conditions
- Family history of hayfever/other atopic conditions
Presentation
The most predominant feature is usually eye itching. Other features are:
- Watery eyes
- Conjunctival redness
- Conjunctival swelling
- Eyelid oedema
They may have symptoms of associated atopic conditions:
- Rhinitis/rhinosinusitis – nasal symptoms may be present
- Asthma
- Urticaria
- Eczema
Investigations
Diagnosis is usually clinical, based on history, examination, and fundoscopy. Investigations are indicated if there is any diagnostic doubt. Investigations may involve conjunctival swabs, skin prick testing, serum IgE etc.
Management
- 1st-line: topical/systemic antihistamine
- Topical antihistamines: emedastine
- Dual-action topical antihistamine and mast-cell stabilisers: olopatadine, ketotifen, epinastine, azelastine
- Systemic antihistamines: cetirizine or loratadine
- 2nd-line: mast cell stabilisers e.g. sodium cromoglicate/nedocromil sodium
Patient Advice
- Patients should avoid wearing contact lenses during the duration of eyedrop treatment
- Patients should not drive or carried out skilled tasks if they take eyedrops until their vision is clear
- Patients should be safety-netted on red flags:
- Reduced visual acuity
- Eye pain, headache, or photophobia
- An inability to open the eye or keep it open
- Red, sticky eyes in neonates within 30 days of birth
- History of trauma or possible foreign body
- Rapidly-progressive discharge – suggests gonococcal infection
- Possible infection with a herpes virus:
- Contact lens use with corneal symptoms e.g. photophobia/watering
Complications
- Reduced quality of life
- Irritability, decreased concentration, and daytime fatigue
- Vernal and atopic keratoconjunctivitis – sight-threatening
- Conjunctivitis associated with contact lens use
- This can lead to keratoconjunctivitis
Prognosis
- Most people respond well to treatment
