Allergic Conjunctivitis

Definition

Conjunctivitis is inflammation of the conjunctiva, the mucous membrane lining the anterior sclera and inner eyelid surfaces, seen in the broad spectrum of conditions, including allergy.

Allergic inflammation of the ocular surface (the lid margins, conjunctiva and cornea is one of the commonest eye disorders.

  • In its mildest form, the conjunctiva becomes inflamed in response to a transient allergen (e.g. pollen in seasonal allergic conjunctivitis), or
  • A persistent allergen (e.g. house dust mite in perennial allergic conjunctivitis) producing unpleasant symptoms but not threatening sight.

At the other end of the spectrum are disorders with blinding complications such as vernal keratoconjunctivitis and Atopic keratoconjunctivitis.

Classification of Allergic Conjunctivitis

  • Seasonal allergic conjunctivitis or Hay Fever
  • Perennial allergic conjunctivitis
  • Atopic keratoconjunctivitis
  • Vernal keratoconjunctivitis
  • Giant papillary conjunctivitis

Clinical Features of Allergic conjunctivitis

History is important

  • Other allergic diseases like asthma or eczema suggest allergic conjunctivitis
  • Use of any topical face/eye preparations — allergic dermatoconjunctivitis
  • Seasonal history suggest hay fever caused by grass, tree or weed pollen, perennial (all year round) symptoms suggest house dust mites, pets especially cats or moulds
  • Use of Antihistamines — may alter clinical picture
  • Contact lens use — irritant or allergic reaction to lens solutions
  • Hallmark symptom of all types of allergic conjunctivitis is itching (pruritus) —more prominent in acute cases
  • Photophobia — with or without decreased visual acuity, usually means keratitis is present
  • It is important to remember that the eyes can be predominantly affected in hay fever, with less rhinitis symptoms, also when patient have been on nasal steroids they will present with conjunctivitis only.

Examination

  • Usually bilateral redness of conjunctiva with swelling (chemosis), periorbital swelling, mucoid discharge
  • There is often eyelid eczema
Three types of conjunctival reaction:

  • Follicles - these appear as small, pale, elevated nodules, most marked in lower tarsal conjunctiva
  • Papillae - are less specific red spots. Each papilla has a central vessel running to the surface
  • Giant Papillae - are less common and much more specific. By definition, they are greater than 1mm in diameter, with domed or flat tops. Large polygonal giant papillae with flat tops form the

‘Cobblestone’ appearance characteristic of vernal conjunctivitis.

Key Features of the Diagnosis of IgE-Mediated Allergic Eye Disease

  • Pruritus (itching), which is usually intense
  • Bilateral involvement, and
  • Associated with atopic respiratory tract disease

The absence of any of these is strong evidence against allergy.

Acute Allergic Conjunctivitis (Seasonal & perennial allergic conjunctivitis)
The pruritus usually distinguishes allergic from other causes of conjunctivitis.
Can de diagnosed by doing a conjunctival scrape looking for eosinophils.

Treatment Options

In perennial conjunctivitis, due to house dust mites or cats, avoidance or allergen reduction measures should be first tried along with antihistamines and if this fails immunotherapy should be considered

Vernal Keratoconjunctivitis

Allergy Library

Upper tarsal surface in
vernal keratoconjunctivitis
showing ‘cobblestone’
appearance.

This is a chronic, bilateral inflammation of the conjunctiva that is most commonly found in children and adolescents. Males tend to be affected more often than females, and it usually resolves by early adulthood. The effects of vernal conjunctivitis can be so severe that blindness may result. Like allergic conjunctivitis it is immune mediated.

It usually occurs in spring and summer months, but in severe cases can be perennial. The most remarkable finding is the intense itching and giant papillae on the tarsal conjunctiva. Ropy mucoid discharge is also a distinguishing sign.

Vernal conjunctivitis probably represents a severe and chronic form of allergic conjunctivitis with more intense symptoms and sequelae.

Treatment of Vernal conjunctivitis includes:

  • Aggressive use of mast cell stabilisers e.g. sodium cromoglycate
  • Topical antihistamines
  • Topical non steroidal anti-inflammatory agents
  • Topical steroids may be necessary in severe cases

Atopic Keratoconjunctivitis (AKC)

Allergy Library

The eyelids in atopic
keratoconjunctivitis.

Atopic dermatitis, although usually manifested peripherally, can have significant eye findings. It has been estimated that up to 25% of patients with atopic dermatitis will often have ocular (eye) involvement.

Eye involvement in AKC include:

  • Conjunctivitis
  • Keratoconjunctivitis (combine inflammation of the cornea and conjunctiva) causing painful, watering, red eye with blurring of vision
  • Cataracts
  • Increased risk of eye infections

The pathophysiology of AKC is not known, but thought to be combination of Type 1 and Type 4 Hypersensitivity reactions

Treatment of AKC

  • Topical steroids for short periods
  • Antihistamines
  • Mast cell stabilizers
  • Cold compresses
  • Careful follow-up to prevent damage to vision

Contact Dermatoconjunctivitis

Contact allergy of the eye and periocular area occurs with a variety of cosmetics, soaps, contact lens solution, and medications. Symptoms include redness of the conjunctiva and periorbital swelling.

Compounds commonly causing allergic contact dermatoconjunctivitis:

  • Neomycin
  • Thiomersal in contact lens solution
  • Atropine
  • Papain
  • Bacitracin
  • Idoxyuridine
  • Ppolymxin B
  • Benzalkonium chloride

Investigation: Patch Test

Treatment: removal and avoidance of the offending agent, cool compresses, antihistamines, and topical steroids. Secondary infections should be adequately treated.

Giant Papillary Conjunctivitis (GPC)

GPC is increasingly more common with the advent of extended wear lenses. GPC is also associated with sutures in the eye and the presence of foreign body

It is thought that the antigen responsible for the inflammatory response is located on the surface of the foreign body. Contact lens wearers secrete a protein that coats the lenses, and it is believed that this protein coating is responsible for the allergic reaction

Clinically, GPC is characterized by the presence of large papillae in the tarsal conjunctiva of the upper lid. GPC resembles vernal conjunctivitis, but almost exclusively associated with contact lens wearers.

Treatment involves steroid, antihistamines, mast cell stabilizers, frequent enzymatic cleaning of the lens. It will usually stop when the patient stops wearing contact lens or the foreign body is removed.

Management of Allergic Conjunctivitis

  • The skin prick test should always be done to confirm the culprit allergen, especially if the patient works with animals
  • A Patch Test is indicated in contact dermatoconjunctivitis
  • Immunotherapy for house dust mite, cat, dog, all pollens
  • Non-specific medical therapy:
    • Cold compresses – may be all that is necessary in mild seasonal and perennial conjunctivitis
    • Mucolytic drops – dissolves the abnormal mucus
    • Treatment of facial eczema in AKC – lid margin hygiene
  • Antihistamines – conventional topical antihistamine
  • Oral antihistamine preferably non sedating
  • Mast cell stabilizers

These compounds are used topically to reduce mast cell degranulation, but also have a wide range of other anti-inflammatory effects that may be relevant. They are usually well tolerated with very few side effects. They offer a preventative action and work most effective if taken before the onset of symptoms, where possible (e.g. at the beginning of the pollen season) or early in the disease process. AS the onset of action is slow (5-7 days) and stinging can occur, patient must be warned that their eyes might feel worse to start with.

IN VKC and AKC, mast cell inhibitors act as steroid sparing agents

Cromolyn sodium is the longest established of these drugs. And both 2% and 4% drops are available for use up to 4 times per day. Nedocromil sodium is a newer, higher potency mast cell stabilizer that compares favourably to cromolyn and can be used twice daily in SAC and PAC.

Lodoxamide is another recently introduced mast cell stabilizer, which may evoke fewer stings than the other. Both nedocromil and lodoxamide have a more rapid onset of action.

  • Steriods
    Topical steroids are very powerful in controlling allergic conjunctivitis, but have potentially sight-threatening side effects.

    Steroids are generally contraindicated in SAR & PAR; occasionally they are used in AKC and VKC.
  • Cyclosporine
    Topical preparation of 2% cyclosporine has been shown to provide a marked reduction in the symptoms and signs of VKC, and cyclosporine is particularly helpful as a steroid-sparing agent.
  • Nonsteroidal anti-inflammatory agents
    Topical NSAIDs appear to have some beneficial effects in allergic conjunctivitis. Topical NSAID are not as potent as steroids but have the advantage of good ocular safety profile and useful in treating non sight threatening conditions like SAR and PAR when mast cell stabilizers and antihistamines fail.
  • Surgery
    Usually limited to the treatment of the sight-reducing corneal disease in AKC & VKC.
  • Laser Surgery
    This can be useful in corneal plaques.

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