Allergic conjunctivitis

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In allergy and immunology, as well as opthalmology, allergic conjunctivitis is "conjunctivitis due to hypersensitivity to various allergens."^[1]

Etiology[edit]

From the immunologic standpoint, it may fall into any of the Gell and Coombs classification of immune reactions types.

The recently cloned interleukin-33 (IL-33) is activated in allergic conjunctivitis, and sensitizes T-lymphocytes to produce IL-4, IL-5 and IL-13 upon challenge with anti-CD3 and anti-CD28.^[2]

Clinical presentation[edit]

Clinically, it tends to be one of four syndromes, one of which has two subtypes (SAC and PAC):^[3]

1. Seasonal and perennial allergic conjunctivitis (SAC) and (PAC): since the conjunctivae and the nasal surfaces are immunologically similar tissue, allergic rhinitis may coexist. The differences between the seasonal and perennial is simple timing: does the condition only occur in an "allergy season", when, for example, levels of a specific pollen are known to be high?
2. Vernal keratoconjunctivitis (VKC): this condition is chronic, and in both eyes, and is associated with a personal or family history of atopy. Atopic comorbidities include asthma, eczema, or seasonal allergic rhinitis
3. Atopic keratoconjunctivitis is also bilateral and chronic, with both similarities to and differences from VKC. It is a Gell and Coombs Type I hypersensitivity disorder. "Atopic dermatitis is a common hereditary disorder that usually has its onset in childhood; symptoms may regress with advancing age. Approximately 3% of the population is afflicted with atopic dermatitis, and, of these, approximately 25% have ocular involvement."^[4]
4. Giant papillary conjunctivitis (GPC) is an immune-mediated inflammatory disorder of superior tarsal conjunctiva. "As the name implies, the primary finding is the presence of "giant" papillae, which are typically greater than 0.3 mm in diameter. It is believed that GPC represents an immunologic reaction to a variety of foreign bodies, which may cause prolonged mechanical irritation to the superior tarsal conjunctiva. Although contact lenses (hard and soft) are the most common irritant, ocular prostheses, extruded scleral buckles, and exposed sutures following previous surgical intervention may precipitate GPC."^[3]

Treatment[edit]

Intranasal corticosteroids when used to treat allergic rhinitis may also help allergic conjunctivitis.^[5]

References[edit]