Prevalence of vernal keratoconjunctivitis: a rare disease?

OBJECTIVE: To determine the prevalence of vernal keratoconjuntivitis (VKC) in Europe. METHODS: A cross-sectional survey was mailed to 3003 ophthalmologists from six countries (Finland, France, Italy, The Netherlands, Norway and Sweden) representing 151.9 million inhabitants. Results were analysed per country, and VKC prevalence for the 15 European member states in 2002 was extrapolated. Six hypotheses were used: disease duration (4 or 8 years) combined with three prevalence hypotheses for non-responding ophthalmologists. RESULTS: The response rate to the survey was 29.5%. The estimates of VKC prevalence in Western Europe (per 10,000 inhabitants) ranged from 1.16 to 10.55. The prevalence of VKC with corneal complications ranged from 0.30 to 2.26. The VKC prevalences per country were in the following ranges: Italy 2.4-27.8, Finland, 0.7-8.4, Sweden 1.2-8.7, The Netherlands 0.6-4.6, France 0.7-3.3 and Norway 0.3-1.9. VKC with corneal complications were: Italy 0.4-4.8, Sweden 0.3-2.4, Finland 0.2-2.8, The Netherlands 0.2-1.6, France 0.3-1.4 and Norway 0.1-1.0. CONCLUSIONS: Based on the most likely hypotheses concerning disease duration and non-responding ophthalmologists' VKC case rate, the best estimate of VKC prevalence in Western Europe is 3.2/10,000 inhabitants. The prevalence of VKC with corneal complications is 0.8/10,000 inhabitants.