Louisa P. Thong, Sophie L. Rogers, Colby Hart, Anthony J. Hall, Lyndell L. Lim

Purpose: Population-based studies of episcleritis and scleritis are sparse. The aim of this retrospective study was to determine the incidence and preva- lence of episcleritis and scleritis in a well-deftned population of metropolitan Melbourne.
Methods: All patients with episcleritis or scleritis seen at the Emergency Department and Ocular Immunology Clinic of the Royal Victorian Eye and Ear Hospital were identifted from November 2014 through to October 2015. Retrospective chart review was conducted to conftrm the diagnosis, establish time of onset and disease subtype. Age and gender- stratifted population data from the Australian Bureau of Statistics 2015 were used to calculate inci- dence and prevalence.
Results: The adult population of Greater Melbourne was 3,592,092 people. During the study period, there were 150 new-onset and 19 prior-onset cases of active episcleritis, and 38 new-onset and 23 prior- onset cases of active scleritis. For episcleritis, this yielded an overall incidence of 4.2/100,000 person- years and an annual prevalence of 4.7/100,000 per- sons. Females aged 25-44 years had a higher inci- dence (p=0.04) and prevalence (p=0.02) of episcleritis. For scleritis, the overall incidence was 1.1/100,000 person-years and the annual prevalence was 1.7/100,000 persons. There were no cases of infectious scleritis. Of those with non-infectious scleritis, diffuse scleritis was the most common (62.3%), followed by nodular (29.5%) and posterior scleritis (8.2%). Most cases of episcleritis were sim- ple (86.4%) with the remaining being nodular.
Conclusion: In this ftrst Australian study, popula- tion rates of episcleritis and scleritis were lower compared to previous U.S. studies and more com- monly affected young to middle-aged females.