The unusual association of inverse retinitis pigmentosa and Fuchs' heterochromic iridocyclitis.

BACKGROUND

Classic retinitis pigmentosa (RP) and other syndromic variants have previously been associated to Fuchs' heterochromic iridocyclitis (FHI). Common immunogenic and inflammatory pathways have been proposed to explain the higher incidence of this uveitic phenomenon in patients with retinal dystrophies without definitive answers. Infrequent variants of RP such as inverse RP have not been previously reported in association with FHI. We believe that finding the way these entities connect can shed some light into their complex pathogenesis and help find ways to foresee and prevent the appearance of complications such as cataract and macular edema.

METHODS

We present a 15 year old mexican male with history of nyctalopia and rapid, progressive visual loss since infancy who had profound hyper and hypopigmented retinal pigment epithelium changes in the posterior pole together with pigment clumping in the macula of both eyes and an electroretinogram pattern consistent of rod-cone dystrophy. He was diagnosed with inverse RP. Three years after his first visit he was found to have a mild asymptomatic non granulomatous anterior uveitis in the right eye with fine stellate keratic precipitates and subtle iris stromal atrophy not associated with iris synechiae and without evidence of posterior uveitis or findings consistent with infectious etiology. Findings were consistent with FHI. As the patient was normotensive, the lens was transparent and there was no clinical evidence of macular edema, the patient was kept under observation without treatment.

CONCLUSIONS

Patients with RP are prone to develop chronic, low grade inflammation responses similar to the ones present in FHI. This association makes us believe that immunogenetic pathways involved in the degenerative process that leads to photoreceptor loss may become a target in the prevention and treatment of inflammatory complications in RP and disease progression. It also suggests FHI may be a triggered response predisposed by an unidentified genetic factor that may be related to genes affected in RP and thus be identified before irreversible complications such as glaucoma occur.