Uveitis is inflammation of the uveal tract (iris, ciliary body and choroid) that can also cause the inflammation of nearby tissues such as the retina, optic nerve and vitreous humour. This condition is an important cause of blindness and visual loss in many countries.

In anatomical terms, the condition is classified by the main site of inflammation as being either anterior uveitis, intermediate uveitis, posterior uveitis or panuveitis. Out of the major pharmaceutical market regions (the US, Canada, France, Germany, Italy, Spain, the UK, Japan and Australia), GlobalData epidemiologists found that the Asia-Pacific (APAC) markets had notably different anatomical distributions of the condition compared to the remaining regions.

This year, North America and Europe have shown the most common form of the condition to be anterior, while the APAC region has shown the most common form to be panuveitis (as shown in Figure 1). In fact, panuveitis currently accounts for almost 50% of all uveitis cases in APAC, but only ranges from around 10% to 20% in North America and Europe. Taking a closer look at the individual APAC markets, GlobalData epidemiologists found that 47% of cases in Japan were panuveitis, while only 5% of cases in Australia were panuveitis. This difference in the percentage of panuveitis cases has led some researchers to question whether Japan is simply an outlier or whether there is a more specific cause for this distribution.

Current research indicates that in Japan, the high prevalence of Vogt-Koyanagi-Harada (VKH) disease, a rare autoimmune disease, is likely the source of the aforementioned differences. According to the National Institutes of Health, one of the most common symptoms of VKH is panuveitis. In an article published in the Orphanet Journal of Rare Diseases in 2016, the incidence of VKH among uveitis cases was 7% in Japan, 1–4% in the US and 3% in Brazil. Future research efforts aimed at improving early diagnosis and treatment options for VKH in Japan will likely result in a shift in the main anatomical site of uveitis, indicating a distribution that is more in line with what is observed in the other major pharmaceutical markets.