Allergic Eye Disease

Inflammation of the conjunctiva caused by an allergic reaction. Types of allergic conjunctivitis commonly seen in primary care include:

• Seasonal allergic conjunctivitis: often associated with hay fever.
• Perennial allergic conjunctivitis: occurs all year because of permanent contact with the allergen, which is often house dust mite or pet dander.
• Other less common forms of allergic eye disease are:
  • Atopic keratoconjunctivitis: is a chronic, bilateral inflammation of conjunctiva and eyelids, which is often associated with atopic eczema.
  • Vernal keratoconjunctivitis: is a rare bilateral chronic disease occurring in children who have a history of atopy.
  • Giant papillary conjunctivitis: is an inflammatory disorder of superior tarsal conjunctiva. It occurs in the presence of an ocular foreign body and is often the result of either soft or hard contact lenses.

Periorbital allergy

• Periorbital allergy may occur due to a variety of causes, e.g. pollen, dust or insect bites.
• Periorbital contact dermatitis or atopic eczema may cause reddening, dryness and scaling of the skin.
• Other causes of periorbital swelling include nephritic syndrome, nephrotic syndrome, angioneurotic oedema, periorbital cellulitis, orbital cellulitis,¹ hypothyroidism and rarer causes such as cavernous sinus thrombosis and dermatomyositis.
• The most important aspect of management is therefore to rule out other causes for periorbital swelling.
• Oral antihistamines are the treatment of choice for swelling caused by periorbital allergy if treatment is required.

• Both perennial and seasonal allergic conjunctivitis are very common. Allergic conjunctivitis is the cause of around 15% of all eye problems presenting in general practice.²
• Vernal keratoconjunctivitis occurs mainly in hot climates, and presents more often in young males.
• Symptoms usually peak prior to the onset of puberty and then gradually resolve over a period of five to ten years.
• Seasonal allergic conjunctivitis and perennial allergic conjunctivitis are often associated with a family history of asthma, eczema or rhinitis.

• Allergic conjunctivitis presents with an intense itch or a burning sensation and with mild photophobia.
• There may be a history of contact with chemicals or eye drops and the history may have a seasonal time course.
• Bilateral red eye, often with a clear watery discharge may be present.
• Oedema in round swellings may be seen on the inside of the eyelid, and lid swelling.

The diagnosis is usually straightforward but other causes of uncomfortable, inflamed eyes must be considered:

• Infective conjunctivitis: viral or bacterial
• Blepharitis
• Uveitis (iritis)
• Acute glaucoma
• Keratitis: often presents with a unilateral, acutely painful, photophobic, intensely injected eye
• Scleritis: severe, boring ocular pain, which may also involve the adjacent head and facial regions
• Episcleritis: relatively asymptomatic acute onset localised redness in one or both eyes.
• Orbital cellulitis
• Foreign body
• Ocular herpes simplex
• Herpes zoster ophthalmicus
• Dry eye syndrome

• The diagnosis can usually be based on a careful history and eye examination.
• Investigations and/or referral are only indicated if there is any doubt in the diagnosis.

Allergic rhinitis may be associated with allergic conjunctivitis.

• Allergen avoidance is usually not practical.
• Cold compresses may be soothing.
• Contact lenses should not be worn if conjunctivitis is present or during a course of topical therapy.

Drugs

• The topical ocular antihistamines, antazoline, azelastine, and emedastine provide rapid relief of the symptoms of allergic conjunctivitis. Topical antihistamines are not appropriate for prolonged use.
• Mast cell stabilizers are recommended for use throughout a period of allergen exposure. Sodium cromoglicate is usually effective but the newer agents, lodoxamide and nedocromil, may be effective in those with an inadequate response to sodium cromoglicate.
• Diclofenac eye drops are also licensed for seasonal allergic conjunctivitis.
• Topical corticosteroids should never be given for an undiagnosed red eye, when visual acuity is impaired, or if there is a history of ocular herpes simplex infection. Long-term use should be avoided because this can result in cataract, glaucoma, and severe bacterial or fungal infections involving the eyelid, conjunctiva, and cornea.
• Oral antihistamines provide relief of symptoms and are particularly useful when there is associated allergic rhinitis.

Complications are very rare, but a severe allergic reaction can lead to corneal ulceration.

Prognosis is excellent with resolution over a variable time course.