Allergic conjunctivitis: current concepts on pathogenesis and management

Allergic conjunctivitis (AC) includes a wide spectrum of clinical entities characterized by different incidence, ageof onset, natural course, clinical outcome and response to treatment. Taken together, they represent one of the mostfrequent ocular surface diseases affecting more than 30% of the young-adult population and show an increasingincidence over the years. Moreover, comorbidities with other systemic atopic conditions such as asthma, atopicdermatitis and rhinitis require a multidisciplinary approach. Recent advances in the knowledge of the pathogenicmechanism overcome the classic role of type I hyper-sensitivity and mast cells’ activation, demonstrating aninvolvement of innate immunity and neuroinflammation in the pathogenesis of the most severe forms such asatopic keratoconjunctivitis (AKC) and vernal keratoconjunctivitis (VKC). Ocular itching, swelling and tearing arethe most frequent symptoms complained by patients with all forms of AC, while photophobia and pain are typicalof the most severe forms, such as VKC and AKC, due to the frequent corneal involvement. Upper tarsal papillaryreaction represents the main clinical sign of AC associated with conjunctival hyperemia and mucous secretion.Diagnosis is based on clinical history and eye evaluation and can be confirmed through allergological tests.Additional ocular exams include specific allergen conjunctival provocation tests and the presence of eosinophils inthe conjunctival scraping. Current treatments of AC include the use of antiallergic eye drops for mild forms, whilerecurrences of ocular surface inflammations with corneal involvement in severe forms require the use of topicalsteroids to avoid visual impairment. Novel steroid sparing therapies such as Cyclosporine A eye drops or topicalTacrolimus have been proposed to improve VKC and AKC management.