Atopic keratoconjunctivitis.

Atopic keratoconjunctivitis (AKC) represents a disease usually classified under the term of allergic conjunctivitis together with seasonal allergic conjunctivitis (SAC), perennial allergic conjunctivitis (PAC) and vernal keratoconjunctivitis (VKC). However, AKC and VKC have clinical and pathophysiological features quite different from SAC and PAC, in spite of some common markers of allergy. This article aims to review personal studies suggesting that allergic conjunctivitis (similarly to asthma, rhinitis and atopic dermatitis) is a heterogeneous disease entity with different preferential pathogenetic mechanisms and a spectrum of clinical expression which varies according to individual cases. AKC and VKC may thus represent a model of atopy quite distinct from the classical type-1 hypersensitivity mechanism.