Allergic eye disease - a clinical challenge

Currently, six basic allergic eye diseases are recognized. In seasonal (SAC ) and perennial allergic conjunctivitis (PAC), the allergic response is med iated predominantly by mast cells, whereas the more severe conditions, vern al (VKC) and atopic keratoconjunctivitis (AKC) and giant papillary conjunct ivitis (GPC), are associated with a preponderance of T cells. Acute allergi c conjunctivitis (AAC) occurs when a large quantity of allergen inoculates the eye and is usually self-limiting. SAG, the most common ocular allergy, is the ocular component of hayfever. PAC in the UK is most commonly caused by the house-dust mite (HDM); diagnosis is confirmed by skin-prick tests, e osinophils in the conjunctival smear, and raised tear or serum total IgE. S AC and PAC can usually be managed with chromone eyedrops and antihistamines . VKC usually presents in children under 10 years of age and mainly affects boys. Sufferers frequently have a personal or family history of atopy. Cor neal involvement can occur in VKC, making it potentially sight-threatening. AKC occurs in atopic adults, and like VKC it affects the cornea. VKC and A KC require steroid treatment under specialist supervision; minimization of the steroid dose can often be achieved with use of a chromone. GPC occurs d ue to repeated contact of the conjunctival surface with a foreign surface, such as contact lenses. Attention to lens hygiene or switching to different lenses and treatment with a chromone are frequently effective. In all alle rgic eye diseases contact with the precipitating allergen should be avoided as far as possible.