Usher syndrome associated with Fuchs' heterochromic uveitis

Background: The purpose of this study is to report two new cases of Usher syndrome associated with Fuchs' heterochromic uveitis (FHU), to confirm our previous observation of the association between FHU and retinitis pigmentosa (RP), and to evaluate if FHU is particularly associated with Usher syndrome. Methods: Retrospective medical record review of all new RP cases at Hadassah Medical Center between the years 2000 and 2007, review of our previously published data, and a meta-analysis of published relevant articles in peer reviewed journals. Results: During the time frame of the study we diagnosed 58 new cases of RP, of whom one male and one female had the typical findings of FHU, and both had Usher syndrome type II. The difference in the occurrence of FHU between the 616 controls and the patients with RP was significant (p∈=∈0.0073, Fisher's exact test). In our combined data, FHU occurred only in two types of RP; RP simplex with an incidence of 0.57%, and Usher syndrome with an incidence of 13.5%. This difference between the incidence of FHU in patients with Usher syndrome and other types of RP was significant (p∈<∈0.0001, Fisher's exact test). Adding up these two cases with what is already published in the literature makes up a total of 17 RP patients with coexisting FHU. Conclusions: This study confirms the association between FHU and RP; and a particularly stronger association with Usher syndrome type II. Although infectious agents seem to play a role, the cause for this significant correlation is still unclear.