Clinical factors related to low prevalence of Fuchs’ uveitis syndrome in Japan

Abstract

Purpose : Fuchs’ uveitis syndrome (FUS), first described by Ernst Fuchs in 1906, manifests chronic, granulomatous, and typically unilateral mild anterior segment inflammation. FUS is also referred to as Fuchs’ heterochromic iridocyclitis. The exact etiology of FUS is unknown, but many studies suggested an infectious theory associated with an inflammatory process to rubella. The prevalence of FUS in most developed countries ranges from 1 to 11%, while that in Japan is 0.5 to 0.7%, which is apparently lower.
In this study, we investigated the frequencies of ocular findings characteristic of FUS in Japanese patients and the clinical history, and examined factors associated with the lower prevalence.

Methods : We retrospectively reviewed the medical records of 160 patients diagnosed with FUS at 14 uveitis-specialized centers in Japan between April 2010 and March 2021.

Results : Mean age at diagnosis was 48.3 ± 15.0 years, and male to female ratio was 81:79, which was almost equal to other countries. Regarding subjective symptoms at initial presentation, decreased visual acuity was the most common at 41.3%, followed by blurred vision at 38.1%, and floaters at 7.5%. The reason for referral was idiopathic uveitis at 61.9%, followed by cataract at 25.0%, and high IOP including glaucoma at 16.3%. FUS was correctly diagnosed in only 14.4%. The most common ocular finding was anterior ocular inflammation at 91.9%, followed by stellate-shaped keratic precipitates at 88.1%, cataract and pseudophakia at 88.1%, diffuse iris atrophy at 84.4%, heterochromia at 53.1%, and increased IOP high glaucoma at 36.3%. Of 160 patients, 155 (96.9%) had unilateral FUS. As treatments of these ocular findings, cataract surgery was performed in 52.5%, glaucoma surgery in 10.6%, and vitrectomy in 13.8%. On the other hand, mean follow-up period at the primary general ophthalmologists before being referred to our uveitis specialty facilities was 31.6 ± 50.9 months.

Conclusions : The characteristics of Japanese FUS patients were
comparable with those reported in other countries, which may suggest that the prevalence of FUS could be higher than that observed in previous Japanese studies. The low prevalence of FUS in Japan may be a result of being overlooked and misdiagnosed as mild idiopathic uveitis, cataract, and/or glaucoma.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.