Keratoconus and allergic diseases among Israeli adolescents between 2005 and 2013.

PURPOSE:The aim of this study was to evaluate the association between keratoconus (KC) and common allergic conditions, such as asthma, atopic dermatitis, and allergic rhinitis in a large-scale database-based epidemiological study. METHODS:We conducted a cross-sectional study to estimate the epidemiologic relationship between KC and allergic diseases. The study population included all Israeli adolescents who underwent medical evaluation by the Israeli Defense Force, between the years 2005 and 2013. The presence of KC was determined by corneal topography read by an ophthalmologist. RESULTS:A statistically significantly increased odds ratio (OR) for the presence of KC was found for asthma [OR: 2.0; 95% confidence interval (CI): 1.6-2.5; P < 0.001], allergic rhinitis (OR: 1.6; 95% CI: 1.3-2.0; P < 0.001), and the combination of allergic conjunctivitis, chronic blepharitis, and vernal keratoconjunctivitis (AC/CB/VKC), for which a particularly strong association was found (OR: 6.0; 95% CI: 4.0-9.2; P < 0.001). No significant association was found between angioedema, urticaria, history of anaphylaxis, allergy to hymenoptera sting or atopic dermatitis, and KC. After stratifying the patients according to the severity of the allergic disease, the association between severe (AC/CB/VKC) and KC was very high (OR: 36.5; 95% CI: 20.4-65.4; P < 0.001). CONCLUSIONS:In this study, we demonstrated a substantial association between (AC/CB/VKC), asthma, allergic rhinitis, and KC, with no significant association between other allergic diseases and KC. The severity of the allergic status is without doubt associated with a greater risk of having KC. The mechanism causing this association is still unclear.