Chronic allergic conjunctivitis

Abstract

Chronic allergic conjunctivitis (CAC) or perennial allergic conjunctivitis (PAC) is the most frequent form of allergy of the conjunctiva that is encountered in Northern Europe, particularly in city areas. Itching, redness of the mucosa, swelling of the lids and tearing are the main symptoms. Seasonal factors and associated rhinitis are often noted. Symptoms may respond to antiallergic drugs. In contrast, there are generally no specific signs of the disease on slitlamp examination. Most of the time the mucosal aspect (papillary, follicular or atrophic type) is common to other forms of conjunctival allergy. Non-specific factors may predispose to the appearance of CAC, such as an intolerance to a contact lens, a local infection, or a trauma of the eye. Astigmatism, heterophoria and photosensitization may also be triggering agents for the appearance of symptoms of an authentic CAC in an atopic patient. The close association between allergic and non-specific factors may explain the possibility of unilateral forms of CAC and, most of all, the frequent association of CAC to other forms of chronic conjunctivitis. The diagnosis relies on good clinical evaluation of both symptoms and signs. Serum IgE levels are elevated in no more than 30% of cases while tear levels of IgE are more often pathological (over 50% of cases); skin-testing remains the best method for confirming the diagnosis. In most cases it indicates an allergy to house dust and/or mites. Elimination of the offending allergen is the first treatment in CAC. Antiallergic drugs are also effective, such as antihistamines and mast cell stabilizers, nedocromil sodium being very efficient in this respect. In cases where this kind of treatment cannot be pursued indefinitely, specific desensitization to house dust or mites is effective and induces a prompt resolution of symptoms, whereas signs will persist a long time. All non-specific factors associated with the allergy should also be carefully considered and treated, although results are better in pure rather than associated clinical forms of CAC.