Differential diagnosis of ocular allergy

The diagnosis of ocular allergy is based mainly on the medical history, the clinical examination and the allergy workup. The differential diagnosis varies according to the clinical form of the condition. Diagnosis of perennial allergic conjunctivitis may be difficult because of nonspecific conjunctival hyper-reactivity, poor specificity of moderate clinical signs and symptoms, and the constant presence of evaporative ocular dryness. One can then consider dry eye due to lachrymal hypo-productivity, mainly caused by Meibomian gland dysfunction and blepharitis. Interior or exterior air pollution may also cause the same clinical picture. Less often, there may be a chronic infection due to Chlamydia trachomatis or Molluscum contagiosum. In difficult cases, the general allergy workup and localized tests such as assay of total lachrymal IgE and conjunctival provocation tests can provide significant information for the duo ophthalmologist-allergist. (C) 2012 Elsevier Masson SAS. All rights reserved.