Epidemiological Characterization of Uveitis in Japan: a Systematic Review.

Purpose: Study the etiologies, behind uveitis, examine the anatomical location, and explore how these causes vary across regions in Japan.

Methods: The systemic review was conducted followed the PRISMA guidelines, searching through databases, like PubMed/MEDLINE, Scopus, Central and Web of Science, from January 1990 to August 2024. Our focus was on studies done in Japan. Presented in either English or Japanese and provided information on uveitis etiologies. We excluded any studies using selfreported data during our selection process.

Results: Out of a total of 1,738 studies initially considered, only 20 met the criteria for inclusion. The majority of uveitis cases were categorized as "unclassified." Sarcoidosis was the most common systemic etiology, followed by VogtKoyanagiHarada (VKH), with Behcet's disease coming next. Most studies showed a greater number of female patients. In Tokyo, sarcoidosis accounts for 8.9% of uveitis cases, making it the most systemic association cause. In contrast, in Hokkaido, while sarcoidosis remains the leading systemic association of uveitis, it is significantly more prevalent at 19.5%.

Conclusion: The findings reveal significant regional variations in the causes of uveitis across Japan, with sarcoidosis playing a major role. These regional differences underscore the importance of considering local factors in the diagnosis and treatment of uveitis. Additionally, the high prevalence of unclassified uveitis cases points to the urgent need for better methods to accurately identify and manage these conditions.